P2E28Drive Motor A Excitation Current Sensor Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2E28 concerns a drive motor with an electrically excited rotor, the type Nissan uses in the Ariya and BMW in its fifth-generation eDrive. Such a rotor carries a field coil that receives direct current through brushes and slip rings; a sensor measures that current for the closed field-control loop. P2E28 means the sensor signal is electrically valid but does not make sense, for instance it disagrees with a second sensor or with what the commanded duty cycle should produce. CARB wants rationality faults stored apart from circuit faults. No manufacturer documents P2E28 publicly, nor its thresholds. Wiring faults are P2E7B, P2E29 and P2E2A; a real overcurrent is P2E2B. Without a trusted reading the field cannot be regulated, so expect reduced or no drive power.
- What you may notice
- Electric drive warning or service message
- Noticeably reduced drive power
- Vehicle may refuse to drive or stop driving
- Likely causes
- LikelyExcitation current sensor drifted (offset or gain no longer correct)
- PossibleFaulty excitation power stage, so actual and expected current differ
- PossibleWorn brushes or dirty slip rings changing the field circuit resistance
- RareInverter or motor control software fault
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €200 – €4,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.