Powertrain, generic (extended)

P28D7 Clutch B Pump Motor Performance

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

P28D7 judges motor and pump of clutch B as one unit: the oil pressure seen by the sensor, or the speed and current the motor needs for it, does not match the target. Getrag's hydraulic plan for the 7DCT300 has both clutch pumps drawing through a common suction filter, with a pressure sensor downstream of both pumps providing feedback. If P28D7 and the clutch A code P28C8 are stored together, the shared filter or the oil level is therefore a natural suspect; P28D7 on its own points more towards the clutch B pump, its gerotor set or leaking seals in the clutch B circuit. An EVS32 study with Hyundai found such on-demand pumps cut actuation energy by 96.5 % in the WLTP versus an engine-driven pump. No manufacturer documents P28D7 publicly.

Likely causes

Clogged common suction filter, especially if P28C8 is stored too

Leaking seals in the clutch B pressure circuit

Worn or contaminated gerotor set of the clutch B pump

Transmission fluid level too low

Symptoms

Clutch B slips or engages late
Transmission warning, gears on clutch B possibly locked out
Unusual humming from the actuator area

Repair estimate

DifficultyHardWorkshop job

Parts and labour€150–1,600

Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

clutch motor bclutch actuator b

References: law.cornell.edu, cti-symposium.world, citelec.org.