P0A29: Hybrid/EV Battery Power Off Circuit High
What to do
Same as the rest of this family: free check on the service plug if recent work applies, qualified workshop for everything else. This is the battery's safety disconnect — not a home diagnosis.
What this code means
The battery power-off circuit reads high — shorted to a supply, or open where the healthy state reads low.
The consequence matches the rest of the family: a disconnection chain the vehicle cannot verify, answered conservatively, sometimes with a refusal to power on at all. Service plug first where recent work makes that plausible, then the wiring. The family's full picture is at P0A27.
Likely causes
Start here
- Wiring shorted to voltage · moderate
- Open circuit in sensor wiring · moderate
- Corroded or loose connector · easy
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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