P0A40
Drive Motor A Position Sensor Circuit
Electrical fault on the resolver or encoder used to determine rotor position of drive motor A. Position is essential for vector control commutation.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: shop_only
Symptoms
- EV/hybrid system warning light on
- Reduced motor power or torque
- Possible limp mode or vehicle shutdown
Common causes
Ordered by how often each turns out to be the cause.
- Resolver failedCommon
- Resolver wiring shielding faultPossible
Parts involved
- Drive Motor A
- Rotor Position Sensor
- Resolver
P0A40 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.