OBD-II code · Powertrain (generic)
P0157 O2 Sensor Circuit Low Voltage (Bank 2 Sensor 2)
The ECU detects abnormally low voltage from the downstream O2 sensor on bank 2. Indicates persistently lean exhaust past the catalyst, open sensor or wiring shorted to ground.
Is it safe to drive with P0157?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyLean condition on bank 2
- PossibleSignal wire shorted to ground
- PossibleDownstream O2 sensor failed
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Repair at a glance
- Difficulty
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.3–1.5 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Oxygen Sensor B2s2, Oxygen Sensor Wiring, Catalytic Converter Bank2
Related codes
- P0144O2 Sensor Circuit Low Voltage (Bank 1 Sensor 3)
- P0158O2 Sensor Circuit Low Voltage (Bank 2 Sensor 2)
- P0164O2 Sensor Circuit Low Voltage (Bank 2 Sensor 3)
- P0154O2 Sensor Circuit No Activity / Slow Response (Bank 2 Sensor 1)
- P0155O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 1)
- P0156O2 Sensor Circuit Malfunction (Bank 2, Sensor 2)
- P0159O2 Sensor Circuit High Voltage (Bank 2 Sensor 2)
- P015AO2 Sensor Delayed Response - Rich to Lean Bank 1 Sensor 1
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.