P28DEClutch B Pressure Sensor 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
- P28DE means the clutch B pressure sensor delivers a voltage above anything a working sensor would show, even at full clutch pressure. Typical causes are a signal line touching a supply or battery feed, a broken sensor ground, or a signal line open at the sensor end where the input uses a pull-up resistor. No manufacturer documents P28DE publicly. In the actuator layout of a Getrag patent the pressure at each clutch is set by the speed of its own pump motor and checked by a pressure sensor, so a falsely high value would lead the controller to under-apply the clutch; an Audi patent shows the same one-sensor-per-clutch idea. Out-of-range checks on this kind of input are a CARB requirement. P28DD is the low fault and P28CF the clutch A version. The module usually disables clutch B.
- What you may notice
- Transmission warning or check engine light on
- Emergency mode with limited gears
- Slipping or weak pull when clutch B is in use
- Likely causes
- LikelySignal wire shorted to the sensor supply or to battery voltage
- PossibleSensor ground open or high resistance at the connector
- PossiblePressure sensor failed with output stuck high
- 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 – €1,800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.