What does code P28D4 mean?

Q: What does code P28D4 mean?

Clutch B Phase U-V-W Circuit/Open. P28D4 is a generic powertrain code that indicates the transmission control module has detected an open circuit or abnormal voltage on the phase U, V, or W wiring for clutch B, which is part of an electrically driven clutch or hybrid transmission system. The computer monitors the current and voltage on each phase and sets this code when the expected electrical signature is missing, often due to a broken wire, poor connection, or failed clutch actuator.

DTC codes / P28xx · Transmission / P28D4

P28D4Clutch B Phase U-V-W Circuit/Open

P28D4 is a generic powertrain code that indicates the transmission control module has detected an open circuit or abnormal voltage on the phase U, V, or W wiring for clutch B, which is part of an electrically driven clutch or hybrid transmission system. The computer monitors the current and voltage on each phase and sets this code when the expected electrical signature is missing, often due to a broken wire, poor connection, or failed clutch actuator.

SystemPowertrain

Code typeGeneric (all makes)

SeverityHigh

Fix difficultyProfessional

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.