What does code P2AC4 mean?

DTC codes / P2Axx · Hybrid propulsion / P2AC4

P2AC4Intake Air O2 Sensor Reference Voltage Circuit Range/Performance Bank 2

This code indicates that the engine computer has detected an abnormal voltage on the reference circuit for the downstream oxygen sensor on bank 2, which is the side of the engine that does not contain cylinder number one. The reference voltage is a fixed baseline supplied by the computer to the sensor, and when the circuit's voltage falls outside the expected range or does not respond as designed, the computer stores this code.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaHybrid propulsion

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.