P1166low severityPowertrain
HO2S Bank 1 Sensor 1 Heater Circuit Fault
on 2016 Honda Pilot 3.5L V6 · AWD
What this code means
The heater circuit in the upstream O2 sensor has a malfunction.
Symptoms
- CEL
- Poor cold-start economy
- Extended warm-up
- Increased emissions
Common causes
- Failed heater element
- Blown fuse
- Open/short wiring
- Corroded connector
Diagnostic steps
- Test heater resistance
- Check fuse
- Inspect wiring
- Test PCM relay
Repair notes
Replace O2 sensor or repair heater circuit.
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