OBD-II code · Powertrain (generic)
P0042 HO2S Heater Control Circuit Bank 1 Sensor 3
Generic electrical fault in the heater control of the bank 1, sensor 3 oxygen sensor (typically a third sensor downstream of multi-stage cat or NOx trap).
Is it safe to drive with P0042?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyHeater element open
- PossibleHeater wiring or connector fault
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–2 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Oxygen Sensor B1s3 Heater, Heater Wiring
Related codes
- P0062HO2S Heater Control Circuit Bank 2 Sensor 3
- P003FA Camshaft Profile Actuator A Control Stuck On Bank 2
- P0040O2 Sensor Signals Swapped Bank 1 Sensor 1/Bank 2 Sensor 1
- P0041O2 Sensor Signals Swapped Bank 1 Sensor 2/Bank 2 Sensor 2
- P0043HO2S Heater Control Circuit Low Bank 1 Sensor 3
- P0044HO2S Heater Control Circuit High Bank 1 Sensor 3
- P0045Turbocharger/Supercharger Boost Control A Circuit/Open
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.