OBD-II code · Powertrain (generic, extended)
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.
Is it safe to drive with P2AC4?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyReference voltage drifted from nominal
- PossibleHigh-resistance contact in connector
- Less likelySensor element aged beyond calibration window
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–4 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Intake Air O2 Sensor B2, Wiring Harness, Ecm
Related codes
- P2AC0Intake Air O2 Sensor Reference Voltage Circuit Range/Performance Bank 1
- P2AC1Intake Air O2 Sensor Reference Voltage Circuit Low Bank 1
- P2AC2Intake Air O2 Sensor Reference Voltage Circuit High Bank 1
- P2AC3Intake Air O2 Sensor Reference Voltage Circuit/Open Bank 2
- P2AC5Intake Air O2 Sensor Reference Voltage Circuit Low Bank 2
- P2AC6Intake Air O2 Sensor Reference Voltage Circuit High Bank 2
- P2AC7Charge Air Cooler Coolant Temperature Sensor B Circuit
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.