P0051low severityPowertrain
HO2S Heater Control Circuit Low Bank 2 Sensor 1
on 2021 Mazda Mazda3 2.5L I4 · FWD
What this code means
Low voltage in the Bank 2 Sensor 1 O2 heater circuit.
Symptoms
- Check Engine Light
- Extended warmup emissions
Common causes
- Short to ground
- Faulty sensor
- Corroded connector
Diagnostic steps
- Test voltage
- Check for shorts
- Test resistance
Repair notes
Repair or replace sensor.
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