What does code P28B1 mean?

Q: What does code P28B1 mean?

Cylinder 9 Ion Current Sense Circuit Range/Performance. P28B1 indicates that the engine control module (ECM) has detected an out-of-range or erratic signal from the ion current sense circuit for cylinder 9, which is used to monitor combustion quality and detect misfires. The circuit typically measures ionization current across the spark plug gap after ignition, and this code sets when the voltage or current feedback falls outside the expected performance window.

DTC codes / P28xx · Transmission / P28B1

P28B1Cylinder 9 Ion Current Sense Circuit Range/Performance

P28B1 indicates that the engine control module (ECM) has detected an out-of-range or erratic signal from the ion current sense circuit for cylinder 9, which is used to monitor combustion quality and detect misfires. The circuit typically measures ionization current across the spark plug gap after ignition, and this code sets when the voltage or current feedback falls outside the expected performance window.

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.