OBD-II code · Powertrain (generic)
P0143 O2 Sensor Circuit Malfunction (Bank 1 Sensor 3)
The ECU detects a general electrical fault on the third oxygen sensor in the bank 1 exhaust path (typically located after a second catalyst on diesel or large engines with multi-cat exhausts).
Is it safe to drive with P0143?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySensor aged or failed
- PossibleSensor wiring open or shorted
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 B1s3, Oxygen Sensor Wiring
Related codes
- P0163O2 Sensor Circuit Malfunction (Bank 2 Sensor 3)
- P0140O2 Sensor Circuit No Activity / Slow Response (Bank 1 Sensor 2)
- P0141O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 2)
- P0142O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
- P0144O2 Sensor Circuit Low Voltage (Bank 1 Sensor 3)
- P0145O2 Sensor Circuit High Voltage (Bank 1 Sensor 3)
- P0146O2 Sensor Circuit No Activity / Slow Response (Bank 1 Sensor 3)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.