Powertrain
Definition only
Lights the check engine lamp
P2AC1: Intake Air O2 Sensor Reference Voltage Circuit Low Bank 1
Standardized SAE J2012 code · P2Axx codes
What does P2AC1 mean?
The reference voltage supplied to the intake air oxygen sensor on bank 1 reports a low condition. Lambda measurement on the intake side is unreliable.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Common causes
- High Reference wire shorted to ground
- Medium Internal short in sensor reference
- Low Connector pins corroded - high contact resistance
Likelihood is a general estimate across vehicles; your make and model may differ.
Add your car to see reports of P2AC1 on the same make and model first.
P2AC1 in the community
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