Powertrain, generic (extended)

P28F1 Engine Disconnect Clutch Pressure Sensor Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

A hydraulically applied disconnect clutch often has its own pressure sensor so the controller knows how firmly the clutch is held. Ford fits one to the 10R80 modular hybrid transmission of the 2021 Explorer, Aviator and F-150 hybrids; a Ford bulletin covers fluid seeping out at this sensor because its fasteners worked loose, fixed by retightening them. P28F1 is the general electrical fault of that sensor circuit, used when the module cannot tell low from high, typically an open signal, supply or ground wire or a connector that has lost contact. No manufacturer ties P28F1 to a threshold in public. CARB requires circuit checks on such inputs. Without a valid reading the clutch is run on a model or locked open, so the engine may stay off or engagement turns harsh.

Likely causes

Sensor connector loose, corroded or with a pushed-back terminal
Signal, reference or ground wire of the sensor broken
Pressure sensor electronics failed, possibly after fluid ingress at a leaking seal
Sensor input of the transmission or hybrid control module faulty

Symptoms

  • Hybrid or transmission warning light
  • Engine stays off or engages harshly when it should join in
  • Possible fluid wetness around the sensor

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–2,500
Time0.5–5 h

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

Parts involved

engine disconnect clutch pressure sensorwiring harnesshybrid control module

Related codes

P28F2P28F3P28F4P28F5P2884

References: law.cornell.edu, static.nhtsa.gov, patents.google.com.