P28D4Clutch B Motor Phase U-V-W Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P28D4 covers the circuit of the three motor phases for clutch B in general and is mainly logged when the controller energises a phase and no current returns, meaning the path is broken. Getrag chose brushless ferrite motors without rare earths for this pump-actuator generation and reused them from the 6DCT250; if one winding path is lost, the remaining two cannot turn the rotor smoothly, and the gerotor pump of clutch B stops delivering oil to the clutch piston. Loose crimp terminals, a fractured wire near the actuator, or an internal connection cracked by heat cycles are the usual finds. P28D2/P28D3 describe phases forced low or high; P28C6 is the same fault on clutch A. No manufacturer has published P28D4 details.
- What you may notice
- Clutch B cannot be closed, its gears are blocked
- Fault may appear only on rough roads or when hot
- Transmission warning, MIL depending on make
- Likely causes
- LikelyLoose or spread crimp terminal on a clutch B motor phase
- PossiblePhase wire fractured close to the clutch B actuator
- PossibleInternal winding joint in the clutch B motor cracked by thermal cycling
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €1,300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.