P0137: O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2)
Can you still drive? Yes, this code relates to the downstream monitoring sensor and is safe to drive with. However, repair it before your next emissions test.
What Does P0137 Mean?
Code P0137 indicates that the downstream oxygen sensor on Bank 1 is reading a consistently low voltage, typically below 0.2 volts. This sensor monitors catalytic converter efficiency, and a stuck-low reading can indicate a lean exhaust condition after the converter or a failed sensor. The ECU may incorrectly adjust fuel trims based on this faulty signal.
Need to read your codes?
An OBD-II scanner lets you read and clear diagnostic trouble codes from your vehicle's computer. Most scanners work with any car made after 1996.
Browse OBD-II Scanners on AmazonCommon Causes
- Faulty downstream O2 sensor
- Exhaust leak near the sensor
- Wiring issue causing low signal voltage
- Lean fuel condition reaching downstream sensor
Symptoms
- Check engine light on
- Poor fuel economy
- Failed emissions test
- Slight lean running condition
Diagnostic Steps
- 1Read and document freeze frame data
- 2Monitor Bank 1 Sensor 2 voltage with a scan tool
- 3Check for exhaust leaks between the catalytic converter and the sensor
- 4Inspect O2 sensor wiring for damage or high resistance
- 5Compare upstream and downstream O2 sensor readings
- 6Replace downstream O2 sensor if confirmed faulty
Recommended Parts & Tools
oxygen sensor
O2 sensor socket
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $50 - $300 |
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Frequently Asked Questions
What is Bank 1 Sensor 2?
Bank 1 Sensor 2 is the downstream oxygen sensor located after the catalytic converter on the Bank 1 side of the engine. Its primary job is to monitor catalytic converter efficiency.
Is the downstream O2 sensor less important than the upstream one?
The downstream sensor does not directly control fuel mixture like the upstream sensor, but it monitors converter health. A faulty downstream sensor can still affect long-term fuel trims on some vehicles.
Community Fix Reports
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