P0135 – O2 Sensor Heater Circuit (Bank 1 Sensor 1)
Description
The ECM detects a malfunction in the heater circuit of the upstream O2 sensor on Bank 1.
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View Recommended ScannersSymptoms
- Poor fuel economy
- Rough idle
- Extended time to closed loop
- Check engine light
Causes
- Failed heater element in O2 sensor
- Blown fuse
- Open or shorted wiring
- Poor electrical connection
Diagnosis
- Check O2 heater fuse and power feed
- Measure heater resistance with multimeter
- Backprobe heater power and ground
- Inspect wiring and connector for damage
Repair
- Replace O2 sensor if heater is open or shorted
- Repair or replace damaged wiring
- Replace blown fuse after fixing root cause
