What does code P28A4 mean?

Q: What does code P28A4 mean?

Cylinder 6 Ion Current Sense Circuit. P28A4 indicates that the engine control module has detected an abnormal signal on the ion current sense circuit for cylinder 6. This circuit uses a small sensing voltage across the spark plug gap after combustion to measure ionization, which helps the computer assess combustion quality and detect misfires; the code means the expected current signature is missing, out of range, or implausible.

DTC codes / P28xx · Transmission / P28A4

P28A4Cylinder 6 Ion Current Sense Circuit

P28A4 indicates that the engine control module has detected an abnormal signal on the ion current sense circuit for cylinder 6. This circuit uses a small sensing voltage across the spark plug gap after combustion to measure ionization, which helps the computer assess combustion quality and detect misfires; the code means the expected current signature is missing, out of range, or implausible.

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.