P050E Cold Start Engine Exhaust Temperature Too Low

What does it mean?

This generic powertrain diagnostic trouble code (DTC) generally applies to many OBD-II vehicles. This may include, but is not limited to, vehicles from Ford (Mustang, Escape, EcoBoost, etc.), Dodge, Jeep, Land Rover, Nissan, VW, etc.

When a P050E code is stored, it means the Powertrain Control Module (PCM) has detected an exhaust temperature below the minimum threshold during a cold start. A cold start is a term used to describe a driving strategy used only when the engine is at (or below) ambient temperature.

Based on my professional experience, exhaust gas temperature is only monitored in vehicles equipped with clean diesel propulsion systems.

This code is more common in geographical regions with extremely cold climates.

Exhaust temperature changes are essential for reducing emissions in today’s clean diesel engines. The PCM must monitor the exhaust temperature to ensure the desired action is taken to accomplish these drastic temperature changes.

Diesel Exhaust Fluid (DEF) injection systems are responsible for introducing DEF into the catalytic converter and other areas of the exhaust system. These DEF mixtures cause the necessary increase in exhaust temperatures to burn harmful hydrocarbons and trapped nitrogen dioxide particles in the exhaust system. The DEF injection system is controlled by the PCM.

During a cold engine start, the exhaust temperature should be equal to or close to ambient temperature. If the PCM detects that the exhaust temperature is below ambient temperature, a P050E code will be stored and a Malfunction Indicator Lamp (MIL) may illuminate. In most cases, multiple failures will be required for the MIL to illuminate.

Cold Car:

How severe is this DTC?

When a P050E code is stored, DEF injection is likely to be disabled. This code should be classified as severe and rectified urgently.
What are some of the symptoms of the code?

Symptoms of a P050E engine code may include:

Decreased engine performance
Decreased fuel efficiency
Excessive black smoke from the exhaust
Associated DEF codes

What are some common causes of the code?

Causes

of this code may include:

Faulty exhaust temperature sensor
Burned or damaged exhaust temperature sensor wiring
Moisture trapped inside the exhaust has frozen
PCM programming error or faulty PCM

What are the P050E troubleshooting steps?

I would probably start my diagnosis by researching applicable Technical Service Bulletins (TSBs). If I can find one that matches the vehicle I’m working on, the symptoms presented, and the codes that are stored, it is likely to help me diagnose P050E accurately and quickly.

I will need a diagnostic scanner, an infrared thermometer with a laser pointer, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information to diagnose this code.

The vehicle information source will provide me with diagnostic flowcharts for the P050E, wiring diagrams, connector face views, connector pinout charts, and component testing procedures/specifications. This information will be essential for arriving at an accurate diagnosis.

After a visual inspection of the exhaust temperature sensor wiring and connectors (focusing on wiring routed near high-temperature areas), I would connect the scanner to the vehicle’s diagnostic port and retrieve all stored codes and relevant data. The scanner code data may be useful later in my diagnosis. I would write it down and keep it in a safe place. Now, I would want to clear the codes and test the vehicle (during a cold start) to see if the code resets. The test drive should also displace any moisture that may have been previously trapped in the exhaust system.

Use the DVOM to test the exhaust temperature sensor:

Set the DVOM to the ohms setting
Disconnect the sensor from the wiring harness
Use the manufacturer’s specifications and testing procedures to test the sensor
Discard the sensor if it does not meet the manufacturer’s specifications

If the exhaust temperature sensor is good, test the reference voltage and ground at the exhaust temperature sensor:

With the key on and engine off (KOEO), access the exhaust temperature sensor connector
Set the DVOM to the appropriate voltage setting (reference voltage is typically 5 volts)
Probe the reference pin of the exhaust temperature connector with the DVOM’s positive test lead
Probe the ground pin of the same connector with the DVOM’s negative test lead
The DVOM should read a 5-volt reference (+/- 10%)

If reference voltage is found:

Use the scanner’s data stream display to observe the exhaust temperature
Compare the exhaust temperature displayed on the scanner to the actual temperature you detected using the IR thermometer
If the two differ by more than the maximum allowable threshold, suspect a faulty exhaust temperature sensor
If both are within specifications, suspect a faulty PCM or a PCM programming error

If reference voltage is not found:

With KOEO, connect the DVOM’s negative test lead to a battery ground (with the positive test lead still probing the reference voltage pin of the same connector) to see if you have a voltage problem or a ground problem
A voltage problem will need to be traced back to the PCM
A ground problem will need to be traced back to the appropriate ground junction

The exhaust temperature sensor is often confused with an oxygen sensor
Be cautious when working around a hot exhaust

P050F Brake Assist Vacuum Too Low

What does it mean?

This generic powertrain diagnostic trouble code (DTC) generally applies to many OBD-II vehicles. This may include, but is not limited to, vehicles from Chevrolet, Ford, VW, Buick, Cadillac, etc.

A stored P050F code means that the Powertrain Control Module (PCM) has received an input signal from the Vacuum Brake Sensor (VBS) indicating a condition of insufficient vacuum at the brake booster servo.

Although there are several different types (including hydraulic and electronic) of brake assist systems, this code applies only to those that use engine vacuum and a vacuum brake booster.

The vacuum brake booster is located between the brake pedal and the master cylinder. It is bolted to the cabin firewall (usually in front of the driver’s seat). It is accessible with the hood open. One end of the booster actuator rod protrudes through the firewall and attaches to the brake pedal arm. The other end of the actuator rod pushes the master cylinder piston, which forces brake fluid through the brake lines and triggers braking at each wheel.

The brake booster consists of a metal housing with a pair of large vacuum diaphragms inside. This type of brake booster is called a dual-diaphragm vacuum brake booster. There are vehicles that use a single-diaphragm booster, but this is rare. With the engine running, a constant vacuum is supplied to the diaphragm, which slightly pulls on the brake pedal arm. A one-way check valve (in the vacuum supply hose) prevents vacuum loss when the engine is under load.

While most diesel vehicle applications use a hydra-boost system, others use a vacuum brake booster. Since diesel engines do not produce vacuum, a belt-driven pump is used as the vacuum source. The rest of the booster system works the same way as in a gasoline engine system.

The typical VBS configuration involves a pressure-sensitive resistor inside a small vacuum diaphragm, enclosed in an airtight plastic housing. Vacuum pressure (air density) is measured in kilopascals (kPa) or inches of mercury (Hg). The VBS is inserted through a thick rubber grommet and into the vacuum brake booster housing. When vacuum pressure increases, the VBS resistance decreases. This results in an increase in the VBS circuit voltage. When vacuum pressure decreases, a reverse action occurs. The PCM receives these voltage variations as changes in the vacuum brake booster pressure and reacts accordingly.

If the PCM detects a vacuum level at the brake booster that is not within a defined parameter, a P050F code will be stored and a Malfunction Indicator Lamp (MIL) may be illuminated.

Photo of a brake booster pressure (vacuum) / VBS sensor:

How severe is this DTC?

Low vacuum pressure at the brake booster can lead to increased effort required to activate braking. This could result in a collision with another vehicle. A P050F should be addressed urgently.
What are some of the symptoms of the code?

Symptoms of a P050F engine code may include:

Audible hissing when pressing the brake pedal
Increased effort required to push the brake pedal
Other codes might be stored, including Manifold Absolute Pressure (MAP) codes
Engine drivability issues created by a vacuum leak

What are some of the common causes of the code?

Causes

of this code may include:

Internal leak in the vacuum brake booster
Faulty vacuum brake sensor
Cracked or disconnected vacuum hose
Faulty one-way check valve in the vacuum supply hose
Insufficient engine vacuum

What are the troubleshooting steps for P050F?

First, if there is a hissing sound when you press the brake pedal and the pedal pressure requires increased effort, the brake booster is faulty and will need to be replaced. A loaded booster (sold with the master cylinder included) is recommended because master cylinder leakage is the main contributing factor to booster failure.

You will need a diagnostic scanner, a manual vacuum gauge, a digital volt/ohmmeter, and a reliable source of vehicle information to diagnose a P050F code.

Diagnosing a P050F code would start (for me) with a visual inspection of the booster’s vacuum supply hose. If the hose is connected and in good working order, start the engine (KOER) and secure the vehicle in park or neutral. Carefully remove the one-way check valve (at the end of the vacuum supply hose) from the booster and ensure there is sufficient vacuum reaching the booster. You can use the manual vacuum gauge to test for sufficient vacuum if in doubt.

Engine vacuum requirements can be found in the vehicle information source. If the engine is not producing sufficient vacuum, it will need to be repaired before continuing your diagnosis.
If there is sufficient vacuum at the booster and it appears to be in working order, consult your vehicle information source for component testing procedures and specifications. You should also find wiring diagrams, connector face views, and connector pinout charts. These resources will be necessary for proper diagnosis.
Step 1

With the key on and engine off (KOEO), disconnect the VBS connector and use the positive test lead of the DVOM to check for reference voltage at the appropriate pin of the connector. Test for a ground using the negative test lead. If reference voltage and a ground are present, proceed to Step 2.
Step 2

Use the DVOM (on the ohms setting) to check the VBS. Follow the manufacturer’s testing procedure and specifications to test the VBS. If the sensor does not meet specifications, it is no good. If the sensor is good, proceed to Step 3.
Step 3

With KOER, use the positive probe lead of the DVOM to probe the signal voltage at the VBS connector. Ground the negative test lead to a known good battery ground. The signal voltage should reflect a degree similar to that displayed by the MAP sensor on the scanner’s data display. A chart of vacuum pressure to voltage can also be found in your vehicle information resource. Compare the voltage found at the signal circuit to the appropriate input on the chart. Suspect the VBS is faulty if it does not match the chart. If the voltage is within specifications, proceed to Step 4.
Step 4

Locate the PCM and use the DVOM to ensure that the VBS signal circuit voltage is present there. Probe the VBS signal circuit using the positive test lead of the DVOM. Connect the negative test lead to a good ground. If the VBS signal you found at the VBS connector is not present on the corresponding circuit of the PCM connector, suspect you have an open circuit between the PCM and the VBS.
If all circuits are in order and the VBS meets specifications; you may have a PCM problem or a PCM programming error.

Check Technical Service Bulletins (TSBs) for entries that have the same code and symptoms. The correct TSB can help you considerably in your diagnosis
Only condemn the PCM after all other possibilities have been exhausted

P0510 Closed Throttle Position Switch Malfunction

What does it mean?

The throttle body or linkage of some vehicles may contain a switch that indicates to the Powertrain Control Module (PCM) or Engine Control Module (ECM) when the throttle body is in the closed position. When the throttle body is closed, the switch will be pressed or in the closed position. The PCM uses this switch to keep the engine idling in conjunction with the idle air control valve and/or to enter fuel cut-off mode during coasting.

There may also be a Wide Open Throttle (WOT) switch. If the WOT or closed throttle switch is not engaged, the PCM or ECM may assume that the throttle is partially open, which could affect the air/fuel ratio.

Note: If multiple fault codes are present, such as P0120 (TPS/Pedal Position Sensor A Circuit Malfunction) – there may be an open in the ground circuit or a poor connection to the Throttle Position Sensor TPS).

Symptoms

Symptoms of a DTC P0510 include the illumination of the Malfunction Indicator Lamp (MIL); you will likely not notice any other symptoms.

Causes

Potential causes of a P0510 code include:

  • Open circuit in the wiring harness or loose/dirty connection
  • Faulty closed throttle position switch
  • Altered throttle body idle adjustment screw
  • Faulty ECM

Possible Solutions

Wiring Harness – Disconnect the wiring harness connector at the Throttle Position Sensor (TPS) or closed throttle position switch and the wiring harness connector at the PCM/ECM. Using a digital voltmeter (DVOM) set to the ohms scale, connect the leads to each end of the same wire using a wiring diagram for reference to test continuity between the switch and the PCM/ECM. Resistance should be present in the wiring between the switch and the PCM/ECM; an infinite reading would indicate an open circuit. Repair the open wiring or replace the wiring harness.

Closed Throttle Position Switch – Disconnect the wiring harness connector at the TPS or closed throttle position switch and test continuity using the DVOM with the leads on the two pins of the closed throttle position switch or throttle position sensor, depending on the vehicle. Resistance should be present when the throttle body is in the closed position. If the throttle body linkage does not touch or fully close the switch, an idle adjustment screw setting may have been performed. Readjust the idle adjustment screw to specifications using the factory procedure.

P0512 Starter Request Circuit

What does it mean?

This diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to all vehicles made after 1996 (Dodge, Chrysler, Hyundai, Jeep, Mazda, etc.). Although generic, specific repair steps may vary by make/model.

Whenever I encounter a stored P0512 code, it means the Powertrain Control Module (PCM) has detected a malfunction in the starter request circuit. In this context, “starter” refers to the engine starter.

While the starter receives constant battery voltage through the positive cable, the starter request signal comes from the ignition switch. When the ignition key is inserted into the cylinder and turned to the start position, it activates the electrical portion of the ignition switch and closes a set of heavy-duty contacts, completing the starter request circuit. When the starter request circuit is completed, a battery voltage signal is sent to the starter solenoid (or starter relay on some models). In the vehicle you’re diagnosing, this means a starter request signal must also be sent to the PCM. Since a P0512 code has been stored, the PCM likely didn’t receive the starter request signal.

Once the starter request signal is received by the starter solenoid, the starter begins to spin and a small pinion gear is pushed toward the engine where the pinion teeth engage with the teeth of the flywheel ring gear. This rotates the engine’s crankshaft and helps initiate starting.

Consult a reliable vehicle information source (All Data DIY is excellent) to determine if the vehicle in question has a starter relay. If so, you’ll need to locate the relay and the system wiring diagram. Typically, the ignition switch provides the starter relay with a starter request signal. Once the relay receives this signal, it then provides both the starter and PCM with a starter request signal. After this, the starter and solenoid operate exactly the same as in vehicles without a starter relay.

Even if there are no symptoms, if the PCM doesn’t receive the starter request signal and the engine starts, a P0512 code will be stored and a malfunction indicator light may illuminate. Some vehicles require multiple ignition cycles (with a fault) for the MIL to illuminate.
Severity and Symptoms

If the engine starts normally, a P0512 can be addressed at your convenience. Obviously, if the engine won’t start, the code needs to be treated with some urgency.

Symptoms of a P0512 code may include:

Engine may not start
Delayed starter engagement (starting may require multiple key cycles)
PCM power circuit failure codes or ignition system circuit failure codes may accompany this code
Often there are no symptoms

Causes

Possible causes of this code include:

Faulty ignition switch
Blown fuses or burned fusible links
Defective starter relay
Open or shorted circuits in the starter request circuit
PCM error or PCM programming error

Diagnostic and Repair Procedures

A good starting point is always checking technical service bulletins (TSBs) for your specific vehicle. Your problem might be a known issue with a published manufacturer fix that could save you time and money during diagnosis.

When diagnosing a P0512, you’ll need a diagnostic scanner, digital volt/ohmmeter (DVOM), and a vehicle information source (like All Data DIY).

Begin with a visual inspection of all related wiring and connectors. This is also a good time to check all fuses using the DVOM. Check starter system fuses while the starter is engaged, since fuses in unloaded circuits may appear operational until the circuit is loaded.

Now determine whether the vehicle in question has a starter relay. If it does, a simple and easy test is to replace the starter relay with a known good relay. Since most manufacturers use identical relays for multiple functions, you can swap one relay for another for diagnostic purposes. If the problem is resolved after swapping relays, swap them back and replace the starter relay with a new one.

To test the relay without swapping, consult your vehicle information source and find the starter system wiring diagram. The starter relay connector view will also prove useful. Test for battery voltage input circuit to the starter relay. This circuit should maintain battery voltage when the ignition switch is in the run position (this is called switched voltage). If no voltage is entering the starter relay, check system fuses, fusible links, and wiring from the battery or battery junction box. In most cases, the ignition switch provides the relay with a secondary voltage source signal when the ignition switch is turned to the start position. Simultaneously, the PCM will provide a ground signal to the starter relay. The secondary voltage and ground signals will cause the contacts inside the relay to close, completing the starter request circuit that should send a signal to the starter solenoid and back to the PCM.

Disconnect all related controllers before testing circuit resistance with the DVOM. First test the voltage signal to the relay (from the ignition switch). If it’s not present, suspect a faulty ignition switch or wiring malfunction. If the secondary voltage input is present, check the ground signal input from the PCM. If there’s no ground from the starter relay to the PCM, suspect PCM failure or PCM programming error.

There could also be a wiring malfunction between the PCM and starter relay.

Additional Diagnostic Notes:

This code will rarely appear in vehicles without a starter relay (I’ve never seen it)
To avoid misdiagnosis, once repairs are completed and the code is cleared, operate the vehicle normally until the PCM enters readiness mode or the code resets
Before swapping relays (for diagnostic purposes), ensure they have matching service numbers
Always return relays to their original positions and replace faulty relays with new ones

P0513 Incorrect Immobilizer Key

🚨 Code P0513: Immobilizer Key Not Recognized – Complete Guide

🔍 Meaning of Code P0513

Code P0513 indicates that the PCM (Powertrain Control Module) does not recognize the immobilizer key. This key contains an electronic chip that communicates with the vehicle’s security system. Without recognition, the PCM disables ignition and fuel injection, preventing the engine from starting.

⚠️ Severity of Code P0513

Urgency Level: 🔴 High (Address immediately).

  • Immediate Impact :
  • Engine does not start (Start/No Crank condition).
  • Vehicle immobilized.

🚨 Common Symptoms

  • 🔒 Engine does not start despite a functional starter.
  • 🔄 Flashing security light (key or car with lock icon).
  • 🚨 Check Engine light on.
  • 🔋 Intermittent issues after reset (if key battery is weak).

🔧 Possible Causes

  1. Faulty Key/Fob :
  • Damaged electronic chip.
  • Weak battery (for wireless keys).
  1. Immobilizer Antenna Issues :
  • Faulty coil around the ignition cylinder.
  1. Faulty PCM :
  • Programming error or hardware failure.
  1. Damaged Wiring :
  • Cut wires or corroded connectors between the antenna and PCM.

🛠️ Diagnostic and Repair Steps

1. Check the Key/Fob

  • 🔋 Wireless key: Replace the battery (CR2032/CR2025 models).
  • 🔍 Inspect the key: Cracks, water damage, or missing chip.
  • 🔑 Test a spare key (if available).

2. Inspect the Immobilizer Antenna

  • 📡 Locate the coil around the ignition cylinder.
  • 🔌 Check connectors and wiring (loose, corroded).

3. Use a Diagnostic Scanner

  • 📟 Read associated codes (e.g., B3031 for Honda).
  • 🔄 Reset the system via key relearn functions (often requires professional tool).

4. Check Technical Service Bulletins (TSB)

  • 🔎 Search for TSBs related to P0513 for your model (e.g., Hyundai/Kia for chip issues).

5. Check the PCM

  • 💻 Test PCM power and ground.
  • 🔧 If necessary, reprogram or replace the PCM (via a dealership).

💰 Estimated Costs

Service Cost (USD)
Reprogrammed key 50 – 200
Immobilizer antenna 100 – 300
PCM reprogramming 150 – 500
Professional diagnostic 50 – 100

❓ FAQ: Frequently Asked Questions

Q: Can I start my vehicle with code P0513?
→ A: No. The security system blocks ignition and injection.

Q: How to reset the immobilizer system?
→ A: Follow the factory procedure (e.g., turn ignition on/off 3 times with a valid key).

Q: Can a spare key cause P0513?
→ A: Yes! Unprogrammed or copied keys can trigger this code.

📋 Key Relearning Procedure (Generic Example)

  1. Insert the valid key and turn the ignition to On (without starting).
  2. Wait 10 minutes until the security light turns off.
  3. Turn the ignition to Off, then repeat 2 to 3 times.
  4. Start the engine.

(Consult your vehicle’s manual for the exact procedure.)

🚗 Conclusion: Don’t Get Stranded!

An unresolved P0513 code can immobilize your vehicle. Follow these steps:

  1. Test the key/fob and its power source.
  2. Inspect the immobilizer antenna.
  3. Consult a professional to reprogram the PCM if necessary.

🔧 Pro Tip: Avoid unprogrammed aftermarket keys. Opt for OEM parts for guaranteed compatibility.

P0514 Battery Temperature Sensor Circuit Range

What does it mean?

This generic powertrain diagnostic trouble code can generally apply to all OBD-II equipped vehicles, but appears more frequently in certain Chrysler, Dodge, Jeep, Mitsubishi, and Toyota vehicles.

Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

The Battery Temperature Sensor (BTS) is typically located near the battery/mounted inside the PCM (Powertrain Control Module). The BTS sensor converts the temperature of the air surrounding the battery into an electrical signal for the Powertrain Control Module (PCM).

The PCM receives this voltage signal to determine the voltage the battery will receive during battery charging based on localized temperatures. This code is set if this input does not match the normal engine operating conditions stored in the PCM’s memory, even for a second, as indicated by this diagnostic code. It also examines the voltage signal from the BTS sensor to determine if it is correct at initial key-on.

Code P0514 indicates a problem with the range or performance in the circuit and could have been set due to mechanical issues (physical damage to the sensor itself, thus causing an electrical fault) or electrical issues (BTS sensor circuit). These cannot be overlooked during the troubleshooting phase, especially when dealing with an intermittent problem.

P0516 is set when the voltage at the sensor remains below a defined level (usually under 0.3 V) for too long. This code is generally considered an electrical circuit problem.

P0517 is set when the voltage at the sensor remains above a defined level (usually above 4.8 V) for too long. This code is generally considered an electrical circuit problem.

Troubleshooting steps may vary depending on the manufacturer, BTS sensor type, and wire colors. An example of a battery temperature sensor is shown here:

How severe is this DTC?

The severity in these cases will not be serious. Since these are electrical failures, the PCM can compensate for them adequately.
What are some of the symptoms of the code?

Symptoms of a P0514 trouble code may include:

Malfunction Indicator Lamp (MIL) illuminated
Low charging voltage indicated possible
Charge light illuminated

What are some of the common causes of the code?

Causes

of this P0514 code may include:

14 15 Open in the signal circuit to the BTS sensor – possible
14 15 Short to voltage in the BTS sensor signal circuit – possible
14 15 16 Short to ground in the BTS sensor signal circuit – possible
17 Short to power in the BTS sensor signal circuit – possible
14 15 Faulty BTS sensor – probable
16 17 Faulty BTS sensor – possible
Failed PCM – unlikely

What are the P0514 troubleshooting steps?

A good starting point is always to check the Technical Service Bulletins (TSBs) for your vehicle. Your issue may be a known problem with a known fix issued by the manufacturer and can save you time and money when diagnosing.

Next, locate the battery temperature sensor on your vehicle. This sensor is typically located near the battery/mounted inside the PCM. Once located, visually inspect the connector and wiring. Look for chafing, rubbing, bare wires, burns, or melted plastic. Disconnect the connector and carefully inspect the terminals (the metal parts) inside the connector. See if they look burned or have a greenish tint indicating corrosion. Use electrical contact cleaner and a plastic bristle brush if cleaning the terminals is necessary. Let it dry and apply electrical grease where the terminals make contact.

If you have a scan tool, clear the diagnostic codes from memory and see if the P0514 code returns. If it does not, the connections were likely your problem.

If the P0514 code returns, we will need to test the BTS sensor and its associated circuits. With the key off, disconnect the electrical connector from the BTS sensor. Connect a black wire from the digital voltmeter to the ground terminal at the BTS sensor wiring harness connector. Connect the red wire from the digital voltmeter to the signal terminal at the BTS sensor wiring harness connector. Turn the key to the engine-off position. Check the manufacturer’s specifications; the voltmeter should read 5 volts. If not, repair the signal or ground wire, or replace the PCM.

If the previous test was successful and you continue to get a P0514, this would most likely indicate a faulty BTS sensor, although a faulty PCM cannot be ruled out until the BTS sensor has been replaced. If in doubt, seek assistance from a qualified automotive diagnostician. PCMs must be programmed or calibrated to the vehicle to be installed correctly.

Battery Temperature Sensor Circuit P0515

What does it mean?

This generic powertrain diagnostic trouble code can generally apply to all OBD-II equipped vehicles, but appears more frequently in certain Chrysler, Dodge, Jeep, Mitsubishi, and Toyota vehicles.

Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

The Battery Temperature Sensor (BTS) is typically located near the battery/mounted inside the PCM (Powertrain Control Module). The BTS sensor converts the temperature of the air surrounding the battery into an electrical signal for the Powertrain Control Module (PCM).

The PCM receives this voltage signal to determine the voltage the battery will receive during battery charging based on localized temperatures. This code is set if this input does not match the normal engine operating conditions stored in the PCM’s memory, even for a second, as indicated by this diagnostic code. It also examines the voltage signal from the BTS sensor to determine if it is correct at initial key-on.

Code P0515 means that a general malfunction has been detected and could have been set due to mechanical issues (physical damage to the sensor itself, thus causing an electrical failure) or electrical issues (BTS sensor circuit). These cannot be overlooked during the troubleshooting phase, especially when dealing with an intermittent problem.

Troubleshooting steps may vary depending on the manufacturer, BTS sensor type, and wire colors. An example of a battery temperature sensor is shown here:

How severe is this DTC?

The severity in these cases will not be serious. Since these are electrical failures, the PCM can compensate for them adequately.
What are some of the symptoms of the code?

Symptoms of a P0515 trouble code may include:

Malfunction Indicator Lamp (MIL) illuminated
Low charging voltage indicated possible
Charge light illuminated

What are some common causes of the code?

Causes

of this P0515 code may include:

Open in the signal circuit to the BTS sensor – possible
Short to voltage in the signal circuit to the BTS sensor – possible
Short to ground in the BTS sensor signal circuit – possible
Failed BTS sensor – probable
Failed PCM – unlikely

What are the P0515 troubleshooting steps?

A good starting point is always to check the Technical Service Bulletins (TSBs) for your vehicle. Your issue may be a known problem with a known fix released by the manufacturer and can save you time and money when diagnosing.

Next, locate the battery temperature sensor on your vehicle. This sensor is typically located near the battery/mounted inside the PCM. Once located, visually inspect the connector and wiring. Look for chafing, rubbing, bare wires, burns, or melted plastic. Disconnect the connector and carefully inspect the terminals (the metal parts) inside the connector. See if they look burned or have a greenish tint indicating corrosion. Use electrical contact cleaner and a plastic bristle brush if cleaning the terminals is necessary. Let it dry and apply electrical grease where the terminals make contact.

If you have a scan tool, clear the diagnostic codes from memory and see if the P0515 code returns. If not, the connections were likely your problem.

If the P0515 code returns, we will need to test the BTS sensor and its associated circuits. With the key off, disconnect the electrical connector from the BTS sensor. Connect a black wire from the digital voltmeter to the ground terminal at the BTS sensor wiring harness connector. Connect the red wire from the digital voltmeter to the signal terminal at the BTS sensor wiring harness connector. Turn the key to the engine-off position. Check the manufacturer’s specifications; the voltmeter should read 5 volts. If not, repair the signal or ground wire, or replace the PCM.

If the previous test was successful and you continue to get a P0515, this would most likely indicate a faulty BTS sensor, although a faulty PCM cannot be ruled out until the BTS sensor has been replaced. If in doubt, seek assistance from a qualified automotive diagnostician. PCMs must be programmed or calibrated to the vehicle to be installed correctly.

Battery Temperature Sensor Circuit Low

What does it mean?

This generic powertrain diagnostic trouble code can generally apply to all OBD-II equipped vehicles, but appears more frequently in certain Chrysler, Dodge, Jeep, Mitsubishi, and Toyota vehicles.

Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

The Battery Temperature Sensor (BTS) is typically located near the battery / mounted inside the PCM (Powertrain Control Module). The BTS sensor converts the temperature of the air surrounding the battery into an electrical signal for the Powertrain Control Module (PCM).

The PCM receives this voltage signal to determine the voltage the battery will receive during battery charging based on localized temperatures. This code is set if this input does not match the normal engine operating conditions stored in the PCM’s memory, even for a second, as indicated by this diagnostic code. It also examines the voltage signal from the BTS sensor to determine if it is correct at initial key-on.

Code P0516 is set when the voltage at the sensor remains below a defined level (usually under 0.3 V) for too long a period. This code is generally considered an electrical circuit problem.

Troubleshooting steps may vary depending on the manufacturer, BTS sensor type, and wire colors. An example of a battery temperature sensor is shown here:

Battery Temperature Sensor Code

How severe is this DTC?

The severity in these cases will not be serious. Since these are electrical failures, the PCM can compensate for them adequately.
What are some of the symptoms of the code?

Symptoms of a P0516 trouble code may include:

Malfunction Indicator Light (MIL) illuminated
Low charging voltage indicated possible
Charge light illuminated

What are some of the common causes of the code?

Causes

of this P0516 code may include:

Short to ground in the BTS sensor signal circuit – possible
Faulty BTS sensor – possible
Failed PCM – unlikely

What are the P0516 troubleshooting steps?

A good starting point is always to check the Technical Service Bulletins (TSBs) for your vehicle. Your problem may be a known issue with a known fix released by the manufacturer and can save you time and money when diagnosing.

Next, locate the battery temperature sensor on your vehicle. This sensor is typically located near the battery / mounted inside the PCM. Once located, visually inspect the connector and wiring. Look for scratches, rubbing, bare wires, burns, or melted plastic. Separate the connector and carefully inspect the terminals (the metal parts) inside the connector. See if they look burnt or have a greenish tint indicating corrosion. Use an electrical contact cleaner and a plastic bristle brush if cleaning the terminals is necessary. Let it dry and apply electrical grease where the terminals make contact.

If you have a scan tool, clear the diagnostic codes from the memory and see if the P0516 code returns. If it does not, the connections were probably your problem.

If the P0516 code returns, we will need to test the BTS sensor and its associated circuits. With the key off, disconnect the electrical connector from the BTS sensor. Connect a black wire from the digital voltmeter to the ground terminal at the BTS sensor wiring harness connector. Connect the red wire from the digital voltmeter to the signal terminal at the BTS sensor wiring harness connector. Turn the key to the engine-off position. Check the manufacturer’s specifications; the voltmeter should read 5 volts. If not, repair the signal or ground wire, or replace the PCM.

If the previous test was successful and you continue to get a P0516, this would most likely indicate a faulty BTS sensor, although a faulty PCM cannot be ruled out until the BTS sensor has been replaced. If in doubt, seek assistance from a qualified automotive diagnostician. PCMs must be programmed or calibrated to the vehicle to be installed correctly.

Battery Temperature Sensor Circuit High

This text explains the error code P0517, which is a generic OBD-II code indicating a problem related to the Battery Temperature Sensor (BTS).

Summary of Code P0517

🔹 Problem: The PCM (Powertrain Control Module) detects too high a voltage on the BTS sensor (generally > 4.8V).
🔹 Severity: Low – This is mainly an electrical issue, and the PCM can compensate.
🔹 Possible symptoms:

  • Check engine light on
  • Low charging voltage
  • Charge indicator light activated

Possible Causes

  1. Short circuit to power in the BTS sensor circuit
  2. Faulty BTS sensor
  3. Faulty PCM (rare)

Troubleshooting Steps

  1. Check Technical Service Bulletins (TSB) to see if there is a known solution for this issue on your vehicle model.
  2. Inspect the wiring and connector of the BTS sensor (near the battery or integrated into the PCM). Look for exposed, burnt wires, or corrosion on the connectors. Clean and apply electrical grease if necessary.
  3. Clear the error codes with a diagnostic tool and see if the code returns.
  4. Test the electrical circuit of the BTS sensor using a voltmeter:
    • Disconnect the BTS sensor
    • Check the voltage between the signal terminal and ground (should be around 5V)
    • If the voltage is incorrect, check or replace the wiring or PCM
  5. Replace the BTS sensor if the problem persists after electrical tests.

If the problem persists despite these tests, it may be necessary to consult a professional for an in-depth diagnosis.

P0518 Intermittent Idle Air Control Circuit

What Does It Mean?

This diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to all vehicles from 1996 onward (Dodge, Chrysler, Hyundai, Jeep, Mazda, etc.). Although generic, specific repair steps may vary by make/model.

When your OBD-II-equipped vehicle has a malfunction indicator lamp (MIL) and a stored code P0518, it means the powertrain control module (PCM) has detected an intermittent issue with the idle air control (IAC) actuator circuit. If there are other more specific IAC codes, those should be diagnosed and repaired first.

The IAC system centers around a linear servo motor that controls a piston regulating the amount of air allowed to bypass the throttle plate and enter the intake manifold. Controlling the amount of air bypassing the throttle plate helps manage engine idle speed. When the throttle plate is closed (at idle), very little air is allowed into the engine through the throttle body. The engine cannot maintain idle with this small amount of air and would likely stall. An auxiliary air (vacuum) source must be provided so the engine can keep running with the throttle plate closed. Of course, this auxiliary vacuum source would harm engine performance and fuel efficiency when the throttle plate is open (during acceleration). Hence the need for a fully adjustable, PCM-controlled vacuum source.

The IAC valve piston housing is manufactured with two separate openings allowing air to pass through. The IAC valve is typically bolted to the intake manifold, on or near the throttle body. It’s positioned so that when open (piston retracted from the opening), ambient air can flow through it into the manifold, and when closed (piston blocking the opening), ambient air cannot pass through.

An example of an idle air control (IAC) valve:

The IAC is rarely fully open or closed but remains constantly moving, controlled by the PCM. The PCM uses input signals from oxygen sensors, throttle position sensors, and various other sensors to determine how much air should bypass the throttle plate. When the voltage and ground signals to the IAC valve are adjusted (by the PCM), the valve responds accordingly. If engine RPM levels don’t match the desired programmed parameters, a P0518 code will be stored and an MIL may illuminate.

Related idle air control system circuit trouble codes include:

P0508 Idle Air Control System Circuit Low
P0509 Idle Air Control System Circuit High
P0511 Idle Air Control Circuit
P0518 Intermittent Idle Air Control Circuit

Severity and Symptoms

A malfunctioning idle air control system can cause the engine to stall or idle at unexpectedly high RPM. This code should be treated as severe and addressed urgently. Symptoms of a P0518 code may include:

High engine RPM level
Engine stalling, especially at idle
Unusual noises from the throttle body area
Other IAC-related codes

Causes

Possible causes of this code include:

Faulty IAC motor/valve
Engine vacuum leak
Open or shorted IAC control wires or connectors
Carbon buildup in throttle body or IAC valve
PCM programming error or faulty PCM

Diagnostic and Repair Procedures

A good starting point is always checking technical service bulletins (TSBs) for your specific vehicle. Your issue might be a known problem with a published manufacturer fix, potentially saving time and money during diagnosis.

To diagnose a P0518 code, you’ll need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable vehicle information source (All Data DIY will suffice).

Start by inspecting all wiring and electrical connectors in the IAC system, repairing any that are damaged, corroded, or burnt. Also check the engine for vacuum leaks that could contribute to uncontrollable engine RPM levels. If vacuum leaks are found, repair them and recheck the system.

Next, connect the scanner to the vehicle’s diagnostic connector and retrieve all stored codes and freeze frame data. Document this information in case the code is intermittent. Clear the codes and test drive the vehicle to see if the code returns. If other IAC-related codes are stored, diagnose and repair those first. Also check all technical service bulletins and safety recalls for the vehicle and the specific malfunction. After completing repairs, drive the vehicle normally and allow the PCM to enter readiness mode before declaring the problem fixed.

As a simple method to test the IAC system when engine idle speed is very high, carefully unbolt (preserving the gasket or seal) the IAC valve from the engine and use a shop rag and your fingers to control engine idle speed. If you can control a high idle condition after removing the IAC valve, you know the IAC system isn’t functioning properly. If you cannot control idle speed, suspect a significant vacuum leak. Major engine vacuum leaks can include PCV valves/hoses, vacuum hoses, brake booster, check valve or hoses, stuck open EGR valve, EGR gasket leak, or intake manifold gasket leak.

Consult your vehicle information source for the recommended method of testing the IAC motor with the DVOM. Replace the IAC motor/valve if it doesn’t meet manufacturer specifications.

Additional Diagnostic Notes:

Disconnect all related controllers before testing circuit resistance with the DVOM