P0137: O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)
The oxygen sensor is reporting a lean mixture constantly, or its voltage is stuck low. This is the downstream (after the catalytic converter) sensor on bank 1. The downstream sensor mainly monitors the catalytic converter, so this rarely affects how the engine runs.
Green, yellow, red: three ways P0137 can look
The same code can be a quick fix or a reason to pull over. Match your situation to the closest example.
Keep an eye on it
Light on, car drives normally. Safe to drive and schedule the repair.
Schedule a repair
You need to pass inspection or other codes are joining it. Schedule the repair.
Stop and get help
The sensor code is with misfire codes or a flashing light. Deal with the misfire first and stop driving soon.
Symptoms you might notice
- Check engine light
- Usually no driving symptoms
- Failed emissions test
Common causes, cheapest first
- Exhaust leak ahead of the sensor
- Real lean condition (vacuum leak)
- Failed sensor
- Wiring shorted to ground
What you can check before calling
- Look for exhaust leaks or soot near the sensor
- Check that the sensor connector is attached and not melted
A code points to a system, not a part. Replacing parts based on the code alone is how people spend money without fixing the problem. Testing confirms the cause first.
Generic codes (second character 0) mean the same thing on every vehicle. Some manufacturers add their own details, so check service information for your exact vehicle.
More oxygen sensors codes
- P0130
O2 Sensor Circuit Malfunction (Bank 1, Sensor 1) - P0131
O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1) - P0132
O2 Sensor Circuit High Voltage (Bank 1, Sensor 1) - P0133
O2 Sensor Circuit Slow Response (Bank 1, Sensor 1) - P0134
O2 Sensor Circuit No Activity Detected (Bank 1, Sensor 1) - P0135
O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)
Look up another code
Cummins fault code (like 1922), J1939 SPN and FMI (like SPN 3251 FMI 0), or an OBD-II code (like P0420).
Questions
What does P0137 mean?
P0137 means "O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)". The oxygen sensor is reporting a lean mixture constantly, or its voltage is stuck low. This is the downstream (after the catalytic converter) sensor on bank 1. The downstream sensor mainly monitors the catalytic converter, so this rarely affects how the engine runs.
Can I drive with code P0137?
It depends on what the vehicle is doing. Green: Light on, car drives normally. Safe to drive and schedule the repair. Yellow: You need to pass inspection or other codes are joining it. Schedule the repair. Red: The sensor code is with misfire codes or a flashing light. Deal with the misfire first and stop driving soon.
What causes P0137?
The most common causes are: exhaust leak ahead of the sensor; real lean condition (vacuum leak); failed sensor.
Is P0137 a serious code?
It can be. The sensor code is with misfire codes or a flashing light. Deal with the misfire first and stop driving soon.
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