P28F5 Engine Disconnect Clutch Pressure Sensor Circuit Intermittent/Erratic

P28F5 covers a pressure signal from the engine disconnect clutch that jumps, drops out briefly or changes faster than the hydraulics physically allow. Each sample may sit inside the valid band, but the pattern points to a loose contact, a wire that breaks under vibration or heat, or an unstable sensor. No manufacturer documents P28F5 publicly. Ford's bulletin for the 10R80 hybrid gearbox shows that this sensor sits on the outside of the clutch circuit with its own seal and fasteners; a loose fit there leaks fluid and can also disturb the connector. CARB requires checks for erratic input signals. In contrast to P28F2, which concerns a steady but implausible value, P28F5 is about an unsteady one. The driver may notice sporadic warnings and uneven engine engagement.

Likely causes

Symptoms

• Hybrid warning that comes and goes
• Occasional jerk when the engine is coupled in
• Fluid seepage at the sensor in some cases

Repair estimate

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

Parts involved

Related codes

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