P0A29 code meaning
Hybrid/EV Battery Power Off Circuit High
Powertrain system Generic code P0Axx codes Check engine light
What P0A29 means
P0A29 is stored when the voltage on the hybrid battery power-off line sits above its plausible range for longer than allowed, which points to an open line pulled up internally or a short to a supply voltage. No manufacturer explains P0A29 publicly; GM merely names it as a keyword in a generic bulletin on terminal fit. The circuit itself is the hardwired disconnect path that patents describe beside the CAN crash message, and CARB 1968.2 requires monitoring of hybrid components relevant to emissions. Related: P0A28 for a signal too low, P0A27 when the contactors do not follow the command. A stuck-high line can keep the system from powering up or from shutting down correctly.
P0A29 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0A29
- Hybrid system warning light
- Vehicle does not reach ready mode
- High-voltage system stays active after switching off
Common causes of P0A29
- Most likelyOpen power-off line or unplugged connector
- PossiblePower-off line shorted to battery voltage
- PossibleSpread or corroded terminals at the connectors
- Less likelyFaulty input or driver stage in the control module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hybrid battery power off circuitWiring harnessBms
What each part of P0A29 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. |
| 29 | The exact fault in that area. |
What to do next
- Note P0A29 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 P0A29
What does P0A29 mean?
P0A29 means "Hybrid/EV Battery Power Off Circuit High". P0A29 is stored when the voltage on the hybrid battery power-off line sits above its plausible range for longer than allowed, which points to an open line pulled up internally or a short to a supply voltage. It is a generic code, so it means the same on every make.
Is it safe to drive with P0A29?
Drive gently and only to a workshop. With P0A29 the car can go into limp mode (reduced power) to protect itself.
Will P0A29 fail an emissions test?
Yes, it can. P0A29 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 P0A29 to fix?
Difficulty: hard. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will P0A29 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.