P2AC4 — Intake Air O2 Sensor Reference Voltage Circuit Range/Performance Bank 2
The reference voltage supplied to the intake air oxygen sensor on bank 2 reports a range/performance condition. Lambda measurement on the intake side is unreliable.
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Intake air o2 sensor b2
- Wiring harness
- Ecm
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- Reference voltage drifted from nominal
- High-resistance contact in connector
- Sensor element aged beyond calibration window
Possible symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
Related codes
Sources
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.