P0A78
Drive Motor A Inverter Performance
The drive motor A inverter does not deliver commanded torque within tolerance under load, indicating thermal limit or partial IGBT failure.
- 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.
- Thermal derating activeCommon
- Partial IGBT failurePossible
Parts involved
- Inverter
- Drive Motor A
P0A78 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.