P0135Medium severity
O2 Sensor Heater Circuit (Bank 1 Sensor 1)
A fault was detected in the heater circuit of the upstream oxygen sensor on bank 1.
Common causes
- Faulty oxygen sensor heater
- Blown fuse
- Wiring or connector problems
Possible symptoms
- Check Engine Light on
- Longer warm-up enrichment
- Reduced fuel economy
Code breakdown
P — System
Powertrain (engine, transmission, fuel & emissions)
0 — Type
Generic (SAE standard, common to all manufacturers)
1 — Subsystem
Fuel and air metering