P28D4 code meaning
Clutch B Motor Phase U-V-W Circuit/Open
Powertrain system Generic code P28xx codes Check engine light
What P28D4 means
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.
P28D4 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 3.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P28D4
- 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
Common causes of P28D4
- Most 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
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Clutch motor bWiring harnessTCM
What each part of P28D4 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 8 | Area: transmission. |
| D4 | The exact fault in that area. |
What to do next
- Note P28D4 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P28D4
What does P28D4 mean?
P28D4 means "Clutch B Motor Phase U-V-W Circuit/Open". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P28D4?
Drive gently and only to a workshop. With P28D4 the car can go into limp mode (reduced power) to protect itself.
Will P28D4 fail an emissions test?
Yes, it can. P28D4 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P28D4 to fix?
Difficulty: hard. A typical repair takes 0.5 to 3.5 hours of work. This is a job for a workshop.
Will P28D4 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.