What it means
The clutch A motor position signal does not correlate with the commanded commutation. Sensor offset or signal integrity degraded.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The clutch A motor position sensor tracks the actuator rotor so the TCM can match motor commutation to actual movement. P28CC sets when the position signal is present but does not correlate with the commanded commutation, as can occur with sensor offset, electrical noise, or sensor drift.
Common causes
Most likely first.
- Sensor mechanically offset
- Electrical noise on signal line
- Sensor element aged beyond calibration window
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Capture freeze-frame data and compare clutch A motor command, rotor position, and movement in transmission live data for inconsistent correlation.
- Inspect the clutch A position sensor connector and wiring for loose terminals, damaged insulation, poor routing, or contact with sources of electrical interference.
- Check that the sensor is securely mounted and aligned with the clutch A motor rotor.
- Use a scan tool to observe whether the position signal changes smoothly through an actuator movement, following the manufacturer's procedure.
- If alignment and wiring are sound, test the sensor for drift or noise and compare results with the manufacturer's specification.
Common fixes
- Secure the clutch A position sensor and correct its mounting alignment.
- Repair loose, damaged, or poorly routed sensor wiring.
- Clean and secure sensor connector terminals.
- Replace the clutch A position sensor if its output remains offset or erratic after circuit and alignment checks.
Can I keep driving?
Drive only as needed to reach a safe place for diagnosis if the transmission still shifts normally; avoid demanding acceleration because clutch A engagement may become erratic. Stop driving if shifts slip, shudder, or fail, since the transmission may enter limp mode.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.