Powertrain, generic (extended)

P28C8 Clutch A Pump Motor Performance

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P28C8 concerns the motor-and-pump unit of clutch A as a whole: the controller sees that the delivered result, typically the clutch pressure reported by the sensor or the motor effort needed to reach it, does not fit the command. In on-demand designs the gerotor pump is connected straight to the clutch cylinder, so pressure follows pump speed directly; a Hyundai-backed EVS32 study modelled exactly this arrangement and its energy saving. A pump clogged by particles, a worn gerotor set, internal leakage at the piston seals or low oil level make the pump work harder or fall short. No manufacturer documents P28C8 itself in public; Stellantis blames debris jamming the actuator pump for the related P28C7 on the 7HDT300.

Likely causes

Clutch A pump obstructed by abrasion particles
Internal leakage at the clutch A piston or pressure line seals
Worn gerotor set reducing delivery
Low transmission fluid level so the pump draws air

Symptoms

  • Slipping or delayed engagement of clutch A
  • Transmission warning, gears on clutch A may be locked out
  • Audible whine from the actuator under load

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–1,500
Time1–4 h

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

Parts involved

clutch motor aclutch actuator a

Related codes

P28C7P28C9P28CAP2855P2857P28D7

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