P0137 Oxygen sensor circuit low voltage (bank 1, sensor 2)
What P0137 means
The downstream oxygen sensor on bank 1, after the catalytic converter, is reporting a voltage that stays too low. The engine computer cannot use it to check the converter and may see the exhaust as lean.
P0137 is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- Medium
- Typical repair cost
- 60–300 €
- Workshop time
- 0.3–4 h
- Repair difficulty
- Medium
- DIY possible
- Yes
- Check engine light
- Yes
- Affects emissions test
- Yes
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Check engine light on
- Usually no noticeable change in how the car drives
- Catalyst readiness monitor not completing
- Possible failed emissions test at inspection
Common causes
- Worn or failed downstream oxygen sensor
- Exhaust leak near the sensor letting in outside air
- Signal wire shorted to ground
- Engine running lean
Can I keep driving with P0137?
You can keep driving, but have it checked within one to two weeks. The engine is rarely affected, but the catalyst check cannot run and the car may fail its emissions inspection.
What to check first
- Look for exhaust leaks around the catalytic converter and downstream sensor.
- Check fuel trims to rule out a lean-running engine.
- Inspect the sensor wiring for a short to ground.
- Replace the downstream oxygen sensor if no leak or wiring fault is found.
Related codes
- P0136 Oxygen sensor circuit (bank 1, sensor 2)
- P0138 Oxygen sensor circuit high voltage (bank 1, sensor 2)
- P0135 Oxygen sensor heater circuit (bank 1, sensor 1)
- P0139 Oxygen sensor circuit slow response (bank 1, sensor 2)
- P0134 Oxygen sensor circuit no activity detected (bank 1, sensor 1)
- P0133 Oxygen sensor slow response (bank 1 sensor 1)
- P0132 Oxygen sensor circuit high voltage (bank 1, sensor 1)
- P0131 Oxygen sensor circuit low voltage (bank 1, sensor 1)
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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