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.

Code P013D: Slow Response from O2 Sensor (Bank 2 Sensor 2) – Definition

The diagnostic trouble code P013D is a generic powertrain code applicable to most OBD-II equipped vehicles (Toyota, Ford, VW, etc.). It indicates that the Powertrain Control Module (PCM) has detected an abnormally slow response from the downstream oxygen (O2) sensor (post-catalyst) on bank 2. Bank 2 refers to the side of the engine that does not contain cylinder number 1.

Symptoms of Code P013D

This code is considered serious because a faulty O2 sensor directly affects the air-fuel mixture. Symptoms include:

• ⛽ Decreased fuel efficiency (increased consumption)
• ⚡ Poor engine performance (hesitation, loss of power)
• ⚠️ Illumination of the “Check Engine” or “Service Engine Soon” light
• 🔧 Potential for other related diagnostic trouble codes

Possible Causes of Code P013D

Several factors can cause this fault:

• Faulty O2 Sensor: Normal wear or contamination from combustion byproducts.
• Wiring Problems: Cut wires, corroded connectors, disconnected or heat-damaged components from exhaust heat.
• Failing Catalytic Converter: An inefficient catalyst can distort the downstream sensor’s readings.
• Exhaust Leaks: A leak upstream of the downstream sensor allows oxygen in and disrupts its signal.

Diagnosis and Repair Procedures

To diagnose a P013D, you will need an OBD-II scanner, a digital multimeter (DVOM), and a reliable information source (such as AllData or manufacturer technical service bulletins).

Preliminary Steps:

1. Visual Inspection: Carefully inspect the wiring and connectors for the Bank 2 Sensor 2. Look for signs of burning, corrosion, or physical damage.
2. Check for Other Codes: Ensure no other codes (misfires, MAF sensor issues, etc.) are present. Engine performance issues can cause this code.

Scanner and Multimeter Testing:

1. Use your scanner to observe the live data from the relevant O2 sensor.
2. A healthy downstream sensor should display a relatively stable voltage (typically between 0.5 and 0.7V). A slow or flat response confirms the fault.
3. With a multimeter, check the sensor circuit’s voltage and continuity. Caution: Disconnect the PCM connector before testing resistance to avoid damaging it.

Important Notes:

• The downstream (post-catalyst) sensor is naturally less active than the upstream sensor. Do not expect the same rapid fluctuations.
• Always prioritize OEM or equivalent quality parts. Low-quality catalytic converters or sensors often fail prematurely.

Conclusion and Call to Action

A P013D code should not be ignored, as it can lead to increased fuel consumption and damage the catalytic converter. If the diagnostic procedures are beyond your skill level, consult a professional mechanic for an accurate assessment. Promptly repairing this issue will preserve your vehicle’s performance and longevity.

Code P013E: Delayed Response from O2 Sensor – Rich to Lean (Bank 1, Sensor 2)

The generic fault code P013E indicates that the Powertrain Control Module (PCM) has detected an abnormally slow response time from the secondary oxygen (O2) sensor (or post-catalyst) for engine bank 1. This code is applicable to most OBD-II equipped vehicles.

Symptoms of Code P013E

This code is considered serious because a faulty O2 sensor can disrupt the air-fuel mixture and damage the catalytic converter. Symptoms include:

• ⛽ Reduced fuel efficiency (increased consumption)
• ⚡ Lack of engine performance
• ⚠️ Illumination of the Malfunction Indicator Lamp (MIL)
• 🔧 Other related fault codes may be present

Possible Causes of the Fault

Several elements can cause a P013E code:

• 🔴 Faulty or aging O2 sensor (most common cause)
• 🔌 Damaged wiring, oxidized, loose, or corroded connector
• 📦 Faulty or clogged catalytic converter
• 🛢️ Exhaust leak upstream of the sensor

Diagnosis and Repair Procedures

Necessary Tools: OBD2 scanner, digital multimeter (DVOM), technical information source (e.g., AllData).

Step 1: Visual Inspection
Carefully inspect the connector and wiring of the Bank 1, Sensor 2 O2 sensor. Look for signs of burning, corrosion, or physical damage, especially on sections exposed to heat or friction.

Step 2: Code and Live Data Check
Using a scanner, retrieve all fault codes and freeze frame data. Clear the codes and perform a road test to see if P013E returns. If it does, use the “live data” function to observe the signal from the relevant O2 sensor. A slow response or a flat line confirms the fault.

Step 3: Electrical Tests
With a multimeter, check the sensor circuit’s voltage and continuity. Caution: Disconnect the PCM connector before measuring resistance to prevent any damage.

Step 4: Catalytic Converter Check
An inefficient catalytic converter can sometimes be the underlying cause. Compare the activity of the upstream and downstream O2 sensors; the downstream signal should be much more stable.

Important Notes

• A slow O2 sensor can severely damage the catalytic converter, a very expensive component.
• Always prioritize OEM quality replacement parts for optimal longevity.
• Ensure all other codes related to engine operation (misfires, mass airflow sensor, etc.) are repaired first.

🔧 Need Help? If the diagnosis is beyond your skills, it is highly recommended to entrust your vehicle to a professional mechanic equipped with advanced diagnostic tools.

Code P013F: Definition and Meaning

The error code P013F 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 (post-catalytic) oxygen sensor (O2) for Bank 1. Bank 1 refers to the cylinder bank that contains cylinder number 1.

O2 Sensor Operation and Cause of Fault

The oxygen sensor measures the O2 content in the exhaust gases by comparing it to the oxygen in the ambient air. It generates an electrical signal that the PCM uses to adjust the air-fuel mixture and monitor the catalytic converter’s efficiency. A delayed response time means the sensor’s signal takes too long to switch from a “lean” state (low voltage) to a “rich” state (high voltage), or vice versa, which distorts the PCM’s calculations.

Symptoms of Code P013F

This code is considered serious because it directly impacts engine adjustments. Symptoms include:

• ⛽ Increased fuel consumption (reduced fuel efficiency)
• ⚡ Poor engine performance (lack of power, hesitation)
• ⚠️ Malfunction Indicator Lamp (MIL) illumination
• 🔧 Possible appearance of other related fault codes

Possible Causes of Code P013F

Several factors can cause this fault:

• 🔴 Faulty or aging O2 sensor (most common cause)
• 🔌 Wiring problem: damaged, corroded wires, or faulty connectors
• 📦 Failing catalytic converter (causing abnormal readings)
• 🛠️ Exhaust leaks upstream of the sensor

Diagnosis and Recommended Solutions

Diagnosis should start with a visual inspection of the sensor, its connector, and the wiring for any obvious damage. Use an OBD-II diagnostic tool to observe the Bank 1 O2 sensor signal in real-time and verify its slow response. Compare it with the Bank 2 sensor if your vehicle is equipped with one.

Most common solution: Replace the faulty oxygen sensor for Bank 1, Sensor 2. Before replacing, check for exhaust leaks that could skew the diagnosis.

Call to Action

A P013F code should not be ignored, as it can lead to increased fuel consumption and damage the catalytic converter. For an accurate diagnosis and reliable repair, consult a professional mechanic as soon as symptoms appear.