What does code P0899 mean?

Q: What does code P0899 mean?

Transmission Control System MIL Request Circuit High. P0899 indicates that the transmission control module (TCM) has detected an abnormally high voltage on the dedicated circuit it uses to request that the powertrain control module (PCM) illuminate the malfunction indicator lamp (MIL). The TCM monitors this request line and sets the code when the voltage exceeds the expected range, typically because the circuit is shorted to power, open, or the TCM's internal driver has failed.

DTC codes / P08xx · Transmission / P0899

P0899Transmission Control System MIL Request Circuit High

P0899 indicates that the transmission control module (TCM) has detected an abnormally high voltage on the dedicated circuit it uses to request that the powertrain control module (PCM) illuminate the malfunction indicator lamp (MIL). The TCM monitors this request line and sets the code when the voltage exceeds the expected range, typically because the circuit is shorted to power, open, or the TCM's internal driver has failed.

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.