What is the P0133 Code?

The P0133 trouble code is a generic OBD-II powertrain code. It indicates a slow response from the circuit of the oxygen sensor (lambda sensor) located upstream on bank 1 of the engine. While its definition is standardized for all vehicles, specific diagnostic procedures may vary by make and model.

Concretely, this code indicates that the engine control module (ECM) detects that the signal sent by the sensor to adjust the air/fuel mixture is abnormally slow once the engine has reached its normal operating temperature.

Symptoms of the P0133 Code

It is common for no noticeable symptoms to appear, as the fault is often detected preventively by the electronic system. However, some drivers may observe:

• A slight increase in fuel consumption
• Poor acceleration or hesitation
• An irregular idle
• The check engine light illuminated on the dashboard

Possible Causes of the P0133 Fault

Several issues can be the cause of this code:

• Faulty or aging oxygen sensor (the most common cause)
• Damaged wiring: frayed wires, short circuits, or oxidized connectors leading to the sensor
• Exhaust system leak upstream of the sensor
• Air intake leak (unmetered air)
• Failure of the mass air flow (MAF) sensor

Diagnosis and Solutions for Repairing the P0133 Code

Diagnostic Steps

1. Reset the code using a diagnostic scan tool and perform a road test to check if it reappears.
2. Visually inspect the wiring and connector of the Bank 1 Sensor 1 oxygen sensor for any damage.
3. Check for the absence of exhaust leaks at the manifold and pipe upstream of the sensor.
4. Using an advanced diagnostic tool, check the sensor signal: its frequency and amplitude should vary rapidly between 0.1V and 0.9V.
5. Inspect the air filter and verify the proper operation of the MAF sensor.

Repair Solutions

• Replace the faulty oxygen sensor (the most common solution).
• Repair or replace damaged wiring.
• Seal any detected leaks in the exhaust or air intake system.
• Clean or replace the mass air flow (MAF) sensor if necessary.

Conclusion

The P0133 code, although often without immediate symptoms, should not be ignored. A sluggish oxygen sensor can degrade engine performance and increase your fuel consumption in the long term. An accurate diagnosis is recommended to identify the root cause and avoid unnecessary repairs.

⚠️ Tip: Entrust the diagnosis to a professional mechanic equipped with specific tools to accurately analyze the lambda sensor signal. This will ensure an effective and lasting repair.

What is the P0134 fault code?

The generic OBD-II code P0134 indicates no activity detected from the upstream oxygen sensor (lambda sensor) (Bank 1, Sensor 1). The Powertrain Control Module (PCM) detects that the sensor’s voltage is not fluctuating in response to the oxygen content in the exhaust gases, indicating a flat signal or abnormal resistance for more than one minute after startup.

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Severity of the P0134 Fault: Moderate to High

• Immediate negative impact on pollutant emissions and fuel economy.
• Risk of engine malfunction (stalling, rough idle).
• Requires prompt attention to avoid damaging the catalytic converter.

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Symptoms of the P0134 Code

• Check Engine Light illuminated.
• Rough idle or stalling.
• Black smoke from the exhaust (overly rich mixture).
• Noticeable increase in fuel consumption.
• Loss of power or hesitation during acceleration.

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Possible Causes of the P0134 Code

1. Faulty oxygen sensor (sensor or heater circuit failure).
2. Electrical issues:
   • Frayed wires, corroded connectors, or short circuits.
   • Blown fuse for the sensor’s heater circuit.
3. Exhaust leaks upstream of the sensor.
4. PCM failure (rare, check last).

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How to Diagnose the P0134 Code?

Step 1: Visual Inspection

• Check the exhaust system: Look for holes, cracks, or faulty seals before the sensor.
• Inspect the wiring and connector: Check for corrosion, broken wires, or physical damage.

Step 2: Heater Circuit Test

1. Check the associated fuse (refer to the workshop manual).
2. Measure the heater resistance:
   • Disconnect the sensor.
   • Using a multimeter, test the resistance between the heater terminals (typical value: 2-20 Ω).
   • An infinite (open circuit) or zero (short circuit) resistance indicates a faulty sensor.

Step 3: Lambda Sensor Signal Test

1. Use a diagnostic tool:
   • Monitor the sensor voltage in real-time.
   • A voltage stuck around 450 mV confirms inactivity.
2. Simulate a rich/lean mixture:
   • Inject propane (rich) or create an air leak (lean) to force a voltage variation.

Step 4: PCM Verification

• Test the power signals (5V and ground) at the connector.
• If everything is normal, a PCM failure is possible but rare.

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Solutions to Fix the P0134 Fault

1. Replace the oxygen sensor (most common solution).
2. Repair exhaust leaks (replace gaskets, weld).
3. Replace the blown fuse and inspect the electrical circuit.
4. Clean or repair connectors (contact cleaner and dielectric grease).

🔧 Need an accurate diagnosis? Use our tool to find an expert near you.

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Important Precautions and Tips

• Prefer Original Equipment (OE) parts: Generic sensors may cause compatibility issues.
• Check Technical Service Bulletins (TSB) for recurring issues with your vehicle model.
• After repair, reset the PCM and perform a road test over several drive cycles to clear the fault code.

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When Should You Consult a Professional?

Contact a qualified mechanic for:

• A thorough analysis of the circuit and PCM data.
• PCM replacement, only if all other causes have been ruled out.

💡 Unsure about the procedure? Get personalized advice before starting repairs.

Code P0135: Malfunction in O2 Sensor Heater Circuit (Bank 1, Sensor 1)

Fault code P0135 is a generic OBD-II powertrain code that indicates a problem with the upstream oxygen sensor heater circuit (bank 1, sensor 1). This circuit is crucial for reducing the sensor’s warm-up time, allowing it to reach its optimal operating mode (“closed loop”) more quickly and provide accurate readings to the vehicle’s ECU/ECM.

Function of the O2 Sensor Heater Circuit

The oxygen sensor (lambda probe) measures the oxygen content in the exhaust gases. Its integrated heating element allows it to reach its operating temperature (approximately 600°C) quickly after a cold start. If the ECU detects, based on the coolant temperature, that the sensor is taking too long to start switching (sending a signal), it records the fault code P0135.

Symptoms of Code P0135

• The Malfunction Indicator Lamp (MIL) illuminates on the dashboard.
• Increased fuel consumption (decreased efficiency).
• Unstable idle or poor engine performance (especially during cold starts).
• Potentially higher pollutant emissions.
• In some cases, no noticeable symptoms other than the MIL light.

Possible Causes of Fault P0135

Several components can be the source of this code:

• Faulty oxygen sensor: The internal heating element is burnt out (open circuit or short circuit).
• Wiring problem: Damaged, corroded, loose, or short-circuited wires between the sensor and the ECU.
• Faulty connector: Poor contact, oxidation, or damage on the O2 sensor connector.
• Blown fuse: The sensor heater circuit is often protected by a fuse.
• Problem with the ECU (less common): Failure of the engine control module.

Diagnosis and Solutions for Repairing Code P0135

Before replacing parts, a methodical check is essential.

1. Check the fuse: Consult the owner’s manual to locate and inspect the fuse dedicated to the O2 sensor heater circuit.
2. Visually inspect the wiring and connectors: Look for any signs of damage, corrosion, or burning.
3. Test the resistance of the heating element: Using a multimeter, measure the resistance between the heater pins of the O2 sensor (usually the two pins of the same color). Compare the measured value (generally between 2 and 20 Ω) to the manufacturer’s specification. An infinite resistance (open circuit) or zero resistance (short circuit) confirms a faulty sensor.
4. Check the circuit voltage and ground: With the ignition on, check that the supply voltage (12V) reaches the connector and that the ground is good.

Repair Solutions:

• Repair the wiring: If a wire is cut or short-circuited, repair it or replace the damaged section.
• Clean or replace an oxidized or damaged connector.
• Replace the oxygen sensor: If the internal heating element is faulty, replacing the sensor is the only solution. Use a quality part.
• Replace a blown fuse (after identifying and correcting the cause of the short circuit that blew it).

Important Tip: After any repair, clear the fault codes with an OBD2 scanner and perform a road test to verify that code P0135 does not reappear.

Need Help Diagnosing Your Vehicle?

Code P0135 is generally simple to diagnose with the right tools. If you are not comfortable with these steps, consult a professional mechanic for an accurate diagnosis and reliable repair. Avoid driving for a long time with this fault to preserve your fuel consumption and the proper functioning of the engine.

Code P0136: Low Voltage from O2 Sensor (B1S2) – Diagnosis and Solutions

Fault code P0136 is a generic OBD-II powertrain code, indicating a problem with low voltage in the oxygen sensor (lambda sensor) circuit located downstream of the catalytic converter on your engine’s bank 1 (B1S2). Although generic, repair specifics can vary depending on the vehicle’s make and model.

Understanding the Role of the Oxygen Sensor (B1S2)

The second O2 sensor, or downstream lambda sensor, is responsible for monitoring the efficiency of the catalytic converter. It produces an electrical signal varying between 0.1 V (lean mixture) and 0.9 V (rich mixture). The Engine Control Module (ECM) analyzes this voltage to ensure the catalytic converter is functioning correctly. Code P0136 is triggered when the ECM detects an abnormally low voltage from this sensor for an extended period, typically between 2 and 4 minutes.

Symptoms of Code P0136

It is common for no noticeable symptoms to be perceived by the driver. However, you might observe:

• ❌ An illuminated check engine light
• ⛽ A slight increase in fuel consumption
• ⚡ Occasional misfires (in some cases)
• 📉 A decrease in engine performance

Potential Causes of the Fault

Several malfunctions can be the cause of a P0136 code:

• Faulty Sensor: The O2 sensor itself is worn out or out of service.
• Electrical Circuit Problem: A short circuit to ground or a break (open) in the signal circuit.
• Corroded Connector: Oxidized or dirty terminals prevent good electrical contact.
• Exhaust Leak: A leak upstream of the sensor distorts the oxygen level reading.

How to Diagnose and Solve the Problem?

A methodical approach is essential for an effective repair.

1. Visual Inspection: Examine the sensor, its connector, and the wiring harness for damage, corrosion, or burns.
2. Electrical Test: Using a multimeter, check the voltage and continuity of the sensor circuit to identify a possible short circuit or open circuit.
3. Live Data Check: Use an OBD-II scanner to observe the sensor signal in real-time. A flat or abnormal signal often indicates a faulty sensor.
4. Sensor Replacement: If the electrical tests are good, replacing the Bank 1, Sensor 2 O2 sensor is the most likely solution.

Call to Action

Code P0136 should not be ignored. A faulty sensor can lead to increased fuel consumption and prematurely damage your catalytic converter, a very expensive part. Entrust the diagnosis to a professional if you do not have the equipment or expertise to perform these checks safely.

What is the P0137 Code?

The P0137 trouble code is a generic powertrain code (OBD-II) that indicates a problem with the low voltage oxygen sensor (O2) circuit on Bank 1, Sensor 2 (B1S2). This sensor, located after the catalytic converter, monitors the catalyst’s efficiency. The code is triggered when the engine control module (ECM) detects that the sensor’s signal voltage has remained abnormally low for more than two minutes.

Symptoms of the P0137 Code

This fault is often silent. The most common symptom is the illumination of the Malfunction Indicator Lamp (MIL) on the dashboard. In some cases, you might also observe:

• A slight increase in fuel consumption
• A slight decrease in engine performance
• Failure of the emissions test

Possible Causes of the P0137 Code

Several malfunctions can cause the P0137 code:

• Faulty O2 sensor: The most common cause.
• Electrical circuit problem: Short circuit, open circuit, or high resistance in the sensor wiring.
• Exhaust leaks: A leak near the rear sensor distorts the readings.
• Faulty catalytic converter: A clogged or inefficient catalyst.
• Air/fuel mixture problems: Engine running too rich or too lean.
• Faulty fuel pressure regulator: Fuel pressure too high or too low.

Diagnosis and Solutions to Fix the P0137 Code

To diagnose and resolve a P0137 code, follow these steps:

1. Visual Inspection: Check the sensor’s wiring and connector for any signs of damage or corrosion. Inspect the exhaust system for possible leaks.
2. Sensor Test: Using a multimeter or diagnostic tool, measure the O2 sensor’s voltage and resistance to check if it is functioning correctly.
3. Catalyst Check: Check the condition and efficiency of the catalytic converter.
4. Repair: Depending on the identified cause, proceed with replacing the O2 sensor, repairing the wiring or exhaust system, or replacing the catalyst.

Conclusion and Call to Action

Although the P0137 code often does not make your vehicle immediately undrivable, it should not be ignored. A faulty rear O2 sensor can lead to increased fuel consumption and premature damage to your catalyst, an expensive component.

Experiencing this issue? Our team of professionals is equipped to accurately diagnose the origin of the P0137 code on your vehicle and provide you with a reliable repair. Contact us for a personalized quote and get your vehicle back into optimal running condition.

Fault Code P0138: High Voltage from Oxygen Sensor (O2) – Sensor 2, Bank 1

What is the P0138 Code?

Fault code P0138 is a generic OBD-II code related to the powertrain. It indicates an abnormally high voltage from the heated oxygen sensor (HO2S) located after the catalytic converter on engine bank 1.

This downstream sensor (B1S2) monitors the catalyst’s efficiency by comparing oxygen levels with those from the upstream sensor. Code P0138 is triggered when the engine control module (ECM) detects that the sensor voltage consistently exceeds 999 mV for more than 2 minutes.

Symptoms of P0138 Fault

• Malfunction Indicator Lamp (MIL/Check Engine) illuminated
• Often no visible symptoms
• Possible slight increase in fuel consumption
• Unstable engine idle in some cases

Main Causes of Code P0138

Electrical Issues

• Short circuit in the O2 sensor signal circuit
• Damaged wires or melted insulation
• Oxidized or corroded connector

Mechanical Failures

• Faulty or aging oxygen sensor
• Excessively high fuel pressure
• Sensor ground circuit issue

Diagnosis and Solutions

Preliminary Steps

1. Check the condition of connectors and wiring
2. Visually inspect the sensor for damage
3. Use a diagnostic tool to read real-time data

Corrective Solutions

• Replace the faulty O2 sensor (most common solution)
• Repair or replace damaged wiring
• Clean corroded electrical connectors
• Check and adjust fuel pressure if necessary

FAQ – Frequently Asked Questions

Can I drive with a P0138 code?

Limited driving is possible, but prompt diagnosis is recommended to prevent potential damage to the catalyst.

How much does the repair cost?

Replacing an O2 sensor typically costs between €150 and €400 depending on the vehicle model.

Conclusion

Code P0138 usually indicates an electrical problem or a faulty oxygen sensor. Professional diagnosis is recommended to accurately identify the cause before any replacement. Inspection of wiring and connectors should always be the first step.

Need help with this fault code? Consult a qualified mechanic for accurate diagnosis and reliable repair.

Code P0139: Slow Response from Oxygen Sensor Circuit (B1S2)

Fault Meaning

The generic diagnostic trouble code P0139 is an OBD-II code related to the powertrain. It indicates a problem with the slow response of the rear oxygen sensor (B1S2), located on the driver’s side (Bank 1). This fault means that the Engine Control Module (ECM) is not receiving or is adjusting the sensor’s signal too slowly, preventing it from effectively regulating the air-fuel ratio once the engine is warmed up.

Symptoms of Code P0139

This fault is often silent, but you might observe:

• A slight increase in fuel consumption
• A subtle drop in engine performance
• The Malfunction Indicator Lamp (MIL) illuminated on the dashboard
• Failure of the emissions test (vehicle inspection)

Possible Causes of Fault P0139

Several factors can trigger this code:

• Faulty oxygen sensor: Natural wear or contamination (oil, silicone, fuel).
• Wiring problem: Frayed, broken, shorted wires, or an oxidized connector.
• Exhaust leaks: A leak upstream of the sensor distorts its reading.
• Air leaks: An unmetered air leak in the intake disrupts the mixture.
• Mass Air Flow (MAF) sensor failure: Incorrect values sent to the ECM.

Diagnosis and Solutions for Repairing Code P0139

Start with a logical diagnostic procedure:

1. Code Reset: Clear the code from the ECM using an OBD2 scanner. If it doesn’t return, it might have been a temporary fault.
2. Visual Inspection: Examine the connector, wiring, and sensor for obvious damage. Check the exhaust pipe for leaks.
3. Checking for Air Leaks: Inspect the hoses and intake system for leaks.
4. Advanced Testing (with diagnostic tool): Use an oscilloscope or a scanner capable of graphing to analyze the sensor signal’s frequency and amplitude. A slow or flat signal confirms its failure.
5. Sensor Replacement: If all other causes are ruled out, replacing the Bank 1 Sensor 2 oxygen sensor is the most likely solution.

Conclusion and Call to Action

Although the vehicle may seem to run normally, ignoring a P0139 code can lead to increased fuel consumption and potentially damage the catalytic converter over time. If you don’t have the necessary tools or expertise, entrust the diagnosis to a professional mechanic for an accurate and cost-effective repair.

Need help diagnosing or replacing your sensor? Check out our buying guide to choose the right sensor or contact our online community of experts for personalized advice.

What is the P013A Code?

The P013A trouble code is a generic OBD-II code related to the powertrain. It indicates that the Powertrain Control Module (PCM) has detected a slow response from the downstream oxygen sensor (post-catalytic converter) on Bank 1 (the engine side containing cylinder #1) during the transition from a rich to a lean air-fuel mixture.

Symptoms of the P013A Code

This code is considered serious and should not be ignored. Common symptoms include:

• 📈 Decreased fuel efficiency (increased fuel consumption)
• ⚙️ Poor engine performance (loss of power, hesitation)
• ⚠️ Illumination of the Check Engine Light (Service Engine Soon)
• 🔍 Appearance of other related trouble codes

Possible Causes of the P013A Code

Several failures can cause this code:

• 🔧 Faulty or aging O2 sensor (most common cause)
• 🔌 Wiring or connector issues (cut, burned, or corroded wires)
• 📦 Failing catalytic converter
• 🛠️ Exhaust system leaks

Diagnosis and Repair Procedures

To diagnose a P013A code, you will need an OBD2 scanner, a digital multimeter (DVOM), and a reliable information source (such as AllData or a repair manual).

Preliminary Steps:

1. Visually inspect the O2 sensor wiring and connectors for any obvious damage.
2. Check for exhaust leaks upstream of the sensor.
3. Using the scanner, clear the codes and perform a road test to see if the P013A code returns.

O2 Sensor Testing:

1. Start the engine and let it reach normal operating temperature.
2. Use the live data stream function of your scanner to observe the signal from the relevant O2 sensor (Bank 1, Sensor 2).
3. A properly functioning downstream sensor should display a relatively stable signal. A slow response or non-varying voltage can confirm the failure.
4. For further verification, use a multimeter to test the sensor circuit’s voltage and continuity. Remember to disconnect the PCM connector before testing resistance to avoid damaging it.

Related Codes

Other codes related to slow O2 sensor responses include: P013B, P013C, P013D, P014C, P014D, P014E, P014F.

Conclusion and Call to Action

A P013A code indicates a performance issue with the engine management system that affects emissions and fuel consumption. While replacing the O2 sensor is often the solution, an accurate diagnosis is essential to avoid unnecessary repairs.

💡 Tip: If you are not comfortable with these procedures, it is highly recommended to consult a professional mechanic for an accurate diagnosis. Use our online tool to get a personalized quote.

What is the P013B Code?

The P013B trouble code is a generic powertrain code applicable to most OBD-II equipped vehicles (GMC, Chevrolet, Ford, Dodge, Chrysler, VW, Toyota, Honda, etc.). It indicates that the Powertrain Control Module (PCM) has detected a slow response from the downstream oxygen (O2) sensor (post-catalytic converter) for Bank 1. Bank 1 refers to the side of the engine that contains cylinder number one.

O2 Sensor Operation and Cause of the Fault

The O2 sensor measures the oxygen content in the exhaust gases. It generates an electrical signal that the PCM uses to adjust the air-fuel mixture and monitor the catalytic converter’s efficiency. If the signal switches too slowly between “rich” and “lean” states for a predefined duration, the P013B code is stored, and the Malfunction Indicator Lamp may illuminate.

Severity and Symptoms of Code P013B

This code is considered serious because a faulty O2 sensor can degrade performance and damage the catalytic converter. Symptoms include:

• ⛽ Increased fuel consumption
• ⚡ Engine power loss
• 🔧 Rough idle
• ⚠️ Check Engine light illuminated
• 📟 Other related trouble codes

Possible Causes of Code P013B

• Faulty O2 sensor (wear, contamination)
• Electrical issues: Damaged wiring, corroded or disconnected connectors
• Failing catalytic converter (reduced efficiency)
• Exhaust leaks (causing false sensor readings)

Diagnosis and Repair Procedures

Diagnosing a P013B requires tools such as an OBD2 scanner, a digital multimeter, and a technical information source (e.g., AllDataDIY).

Steps to Follow:

1. Visual Inspection: Check the O2 sensor wiring and connectors for signs of burning, corrosion, or damage.
2. Check for TSBs: Look for any Technical Service Bulletins for your specific vehicle model.
3. Live Data Reading: Use the scanner to observe the downstream O2 sensor signal. A slow or flat signal confirms the fault.
4. Electrical Tests: Use a multimeter to check the sensor circuit’s voltage and continuity (Caution: Disconnect the ECU before performing resistance tests).
5. Replacement: If the sensor is faulty, replace it with a quality OEM part.

Important Notes:

• Resolve any other codes related to misfires or the mass air flow sensor first.
• A failing catalytic converter can also cause this code. Check its efficiency using the scanner.
• Downstream O2 sensors naturally have a slower variation than upstream ones once the engine is in closed-loop operation.

Related Codes

Other slow O2 sensor response codes include: P013A, P013C, P013D, P014C, P014D, P014E, P014F.

Conclusion and Call to Action

A P013B code should not be ignored. A faulty O2 sensor can lead to increased fuel consumption and damage the catalytic converter, which is an expensive component.

💡 Tip: If you are not comfortable with these procedures, consult a professional mechanic for an accurate diagnosis. Always use quality parts to ensure the longevity of the repair.

Need help diagnosing your vehicle? Check out our comprehensive guides or contact an auto repair expert today!

Code P013C: Symptoms, Causes, and Solutions

The error code P013C is a generic OBD-II code that indicates a slow response from the downstream oxygen sensor (lambda sensor) on bank 2 (the side not containing cylinder number 1). This fault is detected by the engine control module (PCM) when the sensor signal takes too long to switch from a rich to a lean state.

Symptoms of Code P013C

This code is considered serious because it affects the air-fuel mixture and can lead to:

• ⛽ Increased fuel consumption
• ⚡ Decreased engine performance
• ⚠️ Illumination of the malfunction indicator light (SERVICE ENGINE SOON)
• 🔧 Appearance of other related fault codes

Possible Causes of the Fault

• 🔌 A faulty or dirty oxygen sensor (O2)
• ⚡ A wiring or connector issue (break, short circuit, corrosion)
• 🔥 A failing catalytic converter
• 🛢️ An exhaust system leak

Diagnosis and Repair Procedures

To diagnose a P013C code, you will need an OBD2 scanner, a digital multimeter (DVOM), and a reliable information source (such as AllDataDIY).

1. Visual Inspection: Check the condition of the O2 sensor wiring and connectors, especially near hot or sharp components.
2. Consult Technical Bulletins: Look for any TSBs (Technical Service Bulletins) for your vehicle model.
3. Using the Scanner: Read and record the fault codes and freeze frame data. Clear the codes and perform a road test to see if the fault reappears.
4. Sensor Data Analysis: With the engine at operating temperature, observe the downstream O2 sensor signal. It should be stable (around 0.45V) and not fluctuate like the upstream sensor.
5. Electrical Test: Using a multimeter, check the voltage and continuity of the sensor circuit. Caution: Disconnect the PCM connector before measuring resistance.

Important Notes

• The downstream O2 sensor is less active than the upstream sensor once the engine is in closed-loop operation.
• Always prefer OEM or equivalent quality parts to avoid premature failures.

🔧 Need Help? If the diagnosis is beyond your expertise, do not hesitate to contact a professional mechanic for a thorough check.