P0AA3Hybrid/EV Battery Negative Contactor Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- The negative main contactor switches the negative pole of the traction battery onto the propulsion bus; together with the positive contactor it isolates the pack completely when the car is off. P0AA3 is the general code for this contactor circuit when the fault is not reported more precisely as stuck closed (P0AA4), stuck open (P0AA5) or a control-circuit fault (P0ADD to P0AE0). No manufacturer documents this exact code publicly; GM, Audi, Jeep and Mitsubishi publish the specific siblings. Contact damage from heat and arcing, as described in NHTSA's Mach-E recall query, is the usual background. Expect a hybrid or EV warning and possibly no ready mode; diagnosis belongs to a high-voltage trained workshop.
- What you may notice
- Vehicle does not enter ready mode
- Hybrid or EV system warning with check engine light
- Charging may be refused
- Likely causes
- LikelyNegative contactor or battery junction box worn or damaged
- PossibleFault in the contactor coil wiring or connector
- RareBattery controller driver or 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: €150 – €3,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.