Powertrain, generic (extended)

P28CF Clutch A Pressure Sensor Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P28CF means the voltage from the clutch A pressure sensor climbs above the band a plausible measurement can reach, usually close to the reference or battery voltage. An open ground line is a frequent trigger, because many sensor circuits then float up to the supply level; a signal wire touching the 5-volt or 12-volt feed, or a sensor with a broken internal element, has the same effect. To the controller this would look like maximum clutch pressure, so it cannot trust the closed-loop pump control and normally deactivates clutch A to avoid unintended engagement. The low-side counterpart is P28CE and the general circuit code P28CD. No manufacturer publicly documents P28CF.

Likely causes

Open ground wire of the clutch A pressure sensor
Signal wire shorted to the 5-volt reference or battery voltage
Pressure sensor failed with output stuck high

Symptoms

  • Transmission warning, clutch A taken out of service
  • Pull-away or shifts only on the other clutch

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–1,000
Time0.5–3 h

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

Parts involved

clutch pressure sensor awiring harnesstcm

Related codes

P28CDP28CEP28D0P28DE

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