OBD-II code guide
P0155 Oxygen Sensor Heater Circuit Bank 2 Sensor 1
P0155 means the upstream oxygen sensor heater circuit on bank 2 has a fault.
What it means
The bank 2 upstream oxygen sensor may not heat quickly enough for accurate fuel control.
Common symptoms
- Check engine light
- Poor fuel economy
- Rough cold operation
- Emissions failure
- Usually drivable
Likely causes
- Failed oxygen sensor heater
- Wiring issue
- Blown heater fuse
- Connector damage
- Exhaust heat damage
First checks
- Confirm which bank is bank 2 before replacing parts.
- Inspect heater circuit wiring.
- Check for shared oxygen sensor heater fuses.
- Review fuel trim data.