OBD-II code · Powertrain (generic)
P0156 O2 Sensor Circuit Malfunction (Bank 2, Sensor 2)
Same condition as P0136 but on the downstream sensor of bank 2. The catalyst efficiency monitor for bank 2 cannot run while this fault is active.
Is it safe to drive with P0156?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyDownstream sensor aged
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 Downstream
Related codes
- P0130O2 Sensor Circuit Malfunction (Bank 1, Sensor 1)
- P0136O2 Sensor Circuit Malfunction (Bank 1, Sensor 2)
- P0150O2 Sensor Circuit Malfunction (Bank 2, Sensor 1)
- P0153O2 Sensor Circuit High Voltage (Bank 2 Sensor 1)
- P0154O2 Sensor Circuit No Activity / Slow Response (Bank 2 Sensor 1)
- P0155O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 1)
- P0157O2 Sensor Circuit Low Voltage (Bank 2 Sensor 2)
- P0158O2 Sensor Circuit Low Voltage (Bank 2 Sensor 2)
- P0159O2 Sensor Circuit High Voltage (Bank 2 Sensor 2)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.