P0155 – O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
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Symptoms
- Rough idle
- Hesitation
- Poor acceleration
- High fuel trims
- Check engine light
Causes
- Faulty O2 heater
- Blown fuse
- Wiring issue
- Contaminated sensor
- ECU issue
Diagnosis
- Inspect O2 wiring
- Check heater fuse
- Test sensor resistance
- Scan live data
- Inspect connectors
Repair
- Replace O2 sensor
- Replace fuse
- Repair wiring
- Clean connectors
- Update ECU if needed