What does code P28A9 mean?

Q: What does code P28A9 mean?

Cylinder 7 Ion Current Sense Circuit Range/Performance. P28A9 indicates that the engine control module (ECM) has detected an out-of-range or performance fault in the ion current sense circuit for cylinder 7. The ion current sense system uses a small voltage across the spark plug gap after ignition to measure combustion quality, and this code means the ECM is not seeing the expected signal from that cylinder.

DTC codes / P28xx · Transmission / P28A9

P28A9Cylinder 7 Ion Current Sense Circuit Range/Performance

P28A9 indicates that the engine control module (ECM) has detected an out-of-range or performance fault in the ion current sense circuit for cylinder 7. The ion current sense system uses a small voltage across the spark plug gap after ignition to measure combustion quality, and this code means the ECM is not seeing the expected signal from that cylinder.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaTransmission

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