P28DDClutch B Pressure Sensor Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Set when the voltage from the clutch B pressure sensor falls below the lowest value the part can produce in normal service. Usually the signal line has a short to ground, the sensor supply is missing or the sensor has failed internally. Because the reading lies outside the valid band, the module treats it as an electrical fault rather than as low pressure. No manufacturer documents P28DD publicly. Patents from Getrag and Audi place one pressure sensor at every clutch of a twin-clutch gearbox so the controller can regulate clutch pressure directly; under CARB rules such inputs need an out-of-range check. P28DE is the high counterpart, P28DC the open circuit and P28CE the same fault on clutch A. Shifts that need clutch B may be blocked.
- What you may notice
- Transmission warning or check engine light on
- Transmission in emergency mode, some gears unavailable
- Harsh or delayed engagement
- Likely causes
- LikelySensor signal wire chafed through and shorted to ground
- PossibleSensor supply voltage missing or pulled down by another shorted sensor on the same supply
- PossiblePressure sensor electronics failed
- 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.