P0136: Oxygen Sensor Circuit Malfunction (Bank 1, Sensor 2)

What does the P0136 error code mean?

The P0136 diagnostic trouble code (DTC) stands for "Oxygen Sensor Circuit Malfunction (Bank 1, Sensor 2)." This code is triggered when the powertrain control module detects an abnormal signal from the downstream oxygen sensor. The powertrain control module monitors oxygen levels in the exhaust gases to ensure the catalytic converter functions properly and reduces emissions. If the sensor is malfunctioning, it could provide incorrect data, which affects fuel management and emissions control. 

Why it's important to address the P0136 error code

The downstream oxygen sensor plays a critical role in monitoring the efficiency of the catalytic converter. If this sensor fails, the powertrain control module may not correctly adjust the air-fuel mixture, leading to increased emissions and potential damage to the catalytic converter. 

Ignoring this issue can result in poor fuel economy, failed emissions tests, and costly repairs, especially if the catalytic converter becomes damaged.

Can I safely drive my car with this error code?

While driving with a P0136 code is possible, it’s not advisable. The issue may not immediately affect drivability, but prolonged operation with a faulty oxygen sensor can lead to increased fuel consumption, engine performance issues, and eventual damage to the catalytic converter. If left unchecked, repairs can become costly, and the vehicle is at risk of failing to pass emissions testing.

Common symptoms of the P0136 error code

• Illuminated check engine light
• Decreased fuel efficiency
• Rough idling or engine hesitation
• Failed emissions test
• Possible sulfur (rotten egg) smell from the exhaust

How is the P0136 error code diagnosed?

Diagnosing the P0136 code involves several steps:

• Use an OBD-II scanner: Confirm the P0136 code and check for any related trouble codes.
• Inspect the oxygen sensor and wiring: Check for visible damage, loose connections or corrosion.
• Perform a voltage test: Use a multimeter to check the sensor’s voltage output to ensure it is within the expected range.
• Check the exhaust system: Inspect for leaks that could affect sensor readings.
• Verify functionality of the powertrain control module: If other components check out, the issue may lie with the powertrain control module itself.

How is the P0136 error code repaired?

Repairs for the P0136 code may include:

• Replacing the faulty downstream oxygen sensor.
• Repairing or replacing damaged wiring or connectors.
• Fixing any exhaust leaks that may be affecting sensor readings.
• Cleaning or replacing the catalytic converter if necessary.
• Updating or reprogramming the powertrain control module if it is determined to be faulty.
• Clearing the error code and performing a test drive to resolve the issue.

Related reading

Follow the link below to reach our diagnostic check engine trouble codes catalog:
On-board diagnostics (OBD-II) trouble code directory