P28D3Clutch B Motor Phase U-V-W Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P28D3 is the high-voltage fault on the phase wiring of the clutch B motor: a lead reads above what the inverter pattern should produce, typically because it contacts a positive feed or the upper switch cannot turn off. In the Getrag 7DCT300 five brushless motors share the housing, two for the shift drums, two for the clutch pumps and one for the cooling pump, so motor harnesses run close together and a chafed spot can bridge to a neighbouring supply. Pin corrosion in the connector is a further candidate. P28D2 is the ground-side fault, P28D4 the interruption, and P28C5 the matching clutch A code. Values are not public. The transmission controller usually disables clutch B and drives on the other half.
- What you may notice
- Warning lamp and stored fault code
- Vehicle drives on with only one clutch, gear choice reduced
- Possible jerk when the controller drops clutch B
- Likely causes
- LikelyClutch B motor phase touching a neighbouring positive feed in the harness
- PossibleCorroded pins bridging at the clutch B motor connector
- RareUpper output switch for the clutch B motor stays conducting
- 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: €100 – €1,300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.