The P0137 code is a diagnostic trouble code (DTC) that indicates an issue with the oxygen sensor circuit. Specifically, it denotes that the rear oxygen sensor voltage has remained below 400 millivolts for an extended period, or that the air-fuel ratio sensor is biased toward a lean condition. This can lead to poor fuel economy and increased emissions.
What Does the P0137 Code Mean?
When the powertrain control module (PCM) detects that the voltage from the rear oxygen sensor has remained low for more than twenty seconds, it triggers the P0137 code. This low voltage reading signifies that the sensor may be malfunctioning or that there is an underlying issue affecting sensor performance.
What Causes the P0137 Code?
- Defective oxygen sensor or air-fuel ratio sensor
- Oxygen sensor heater circuit failure
- Exhaust system leaks
- Defective catalytic converter
- Intake air system leaks (including vacuum leaks)
- Low fuel pressure
- Defective engine coolant temperature sensor
- Faulty sensor wiring or circuit issues
- PCM software needs updating
- Defective PCM
What Are the Symptoms of the P0137 Code?
- Illumination of the Check Engine Light
- Rough idle or poor engine performance
- Decrease in fuel economy
- Unpleasant exhaust odor
- In some cases, no noticeable symptoms
How Serious Is the P0137 Code?
The P0137 code is classified as a moderate severity issue. While it may not pose an immediate threat to vehicle safety or functionality, it is advisable to have it diagnosed and repaired promptly to maintain optimal vehicle performance and avoid more severe problems.
How to Diagnose the P0137 Code
Diagnosing the P0137 code involves several steps:
- Record freeze frame data when the code is set.
- Replicate the conditions under which the code was triggered during a test drive.
- Perform a visual inspection of the oxygen sensor and related wiring.
- Use a digital volt-ohm meter (DVOM) to test the sensor’s voltage and heater circuit.
- Look for exhaust leaks upstream of the sensor.
- If necessary, remove the sensor for further inspection.
Common Repairs for the P0137 Code
- Replacing the defective oxygen sensor
- Repairing or replacing damaged wiring and connectors
- Addressing exhaust system leaks
- Replacing a faulty catalytic converter
- Fixing intake air leaks
- Updating PCM software if required
How Much Does It Cost to Fix the P0137 Code?
The cost to repair the P0137 code can vary significantly based on the underlying cause. Basic repairs such as replacing an oxygen sensor can range from $100 to $300, while more complex issues, like replacing a catalytic converter or fixing exhaust leaks, could cost upwards of $600 or more, depending on labor and parts.
Can I Fix the P0137 Code Myself?
While some DIY-savvy individuals may handle simple repairs like replacing the oxygen sensor, diagnosing the root cause of the P0137 code often requires specialized tools and knowledge. If you are not experienced in automotive diagnostics, it is recommended to consult a professional mechanic to ensure the issue is accurately identified and repaired.
