P0AA1 code meaning
Hybrid/EV Battery Positive Contactor Circuit Stuck Closed
Powertrain system Generic code P0Axx codes Check engine light
What P0AA1 means
P0AA1 means the positive main contactor conducts although it should be open, typically because its contacts have welded. GM checks this with all contactors commanded open for over 120 s (or the bus already below 9 % of pack voltage): more than 30 V on the positive bus in 4 of 6 samples sets Type B (two trips, 19OBDG02). Older GM programs test during precharge instead and set Type A after one trip if bus voltage exceeds 80 % (2011) or 60 % (2016) of pack voltage. GM bulletins cover the 2017 Bolt EV and welded contactors on the 2019 Volt; Jeep fixes false sets on the 2023 Grand Cherokee 4xe with software, Mitsubishi lists it as main contactor (+) seizure on the i-MiEV. The car may refuse to start.
P0AA1 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor0.5 to 6 hours
- Clears after repairAfter a drive cycle
Symptoms of P0AA1
- Vehicle will not switch into ready or propulsion-active mode
- Check engine light and service high voltage system message
- Often stored together with P0AA4 or a slow discharge code such as P0C76
Common causes of P0AA1
- Most likelyPositive contactor contacts welded, e.g. after high current or arcing
- PossibleBattery or hybrid controller software (GM Volt 2019, Jeep 4xe updates)
- PossibleFaulty battery disconnect unit (GM Bolt EV bulletin)
- Less likelyBus voltage sensing error making an open contactor look closed
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv battery positive contactorBmsWiring harness
What each part of P0AA1 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| A | Area: hybrid propulsion. |
| A1 | The exact fault in that area. |
What to do next
- Note P0AA1 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0AA1
What does P0AA1 mean?
P0AA1 means "Hybrid/EV Battery Positive Contactor Circuit Stuck Closed". P0AA1 means the positive main contactor conducts although it should be open, typically because its contacts have welded. It is a generic code, so it means the same on every make.
Is it safe to drive with P0AA1?
Drive gently and only to a workshop. With P0AA1 the car can go into limp mode (reduced power) to protect itself.
Will P0AA1 fail an emissions test?
Yes, it can. P0AA1 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0AA1 to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 6 hours of work. This is a job for a workshop.
Will P0AA1 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.