OBD-II code · Powertrain (generic)
P0142 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
The ECU detects an electrical fault in the heater circuit of the downstream oxygen sensor on bank 1. The heater current is out of range, suggesting an open or shorted heater element, blown fuse or wiring fault.
Is it safe to drive with P0142?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySensor heater element open
- PossibleHeater fuse blown
- PossibleHeater wiring or connector fault
Symptoms
- Check engine light on after several drive cycles
- Slightly increased fuel consumption during cold start
- Delayed entry into closed-loop fuel control
- Failed emissions inspection (lambda readiness)
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 B1s2, Oxygen Sensor Heater Fuse, Oxygen Sensor Heater Wiring
Related codes
- P0147O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 3)
- P0162O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)
- P0167O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 3)
- P013FO2 Sensor Delayed Response - Lean to Rich Bank 1 Sensor 2
- P0140O2 Sensor Circuit No Activity / Slow Response (Bank 1 Sensor 2)
- P0141O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 2)
- P0143O2 Sensor Circuit Malfunction (Bank 1 Sensor 3)
- P0144O2 Sensor Circuit Low Voltage (Bank 1 Sensor 3)
- P0145O2 Sensor Circuit High Voltage (Bank 1 Sensor 3)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.