P0A27
Battery Power Off Circuit
- Severity
- High
- Driving
- Drive only to a garage
A fault in the battery power off circuit on a hybrid or electric vehicle. This is the circuit that shuts the high-voltage system down - disconnecting the traction battery when the vehicle is switched off, and in a crash. These systems fail safe, so the usual result is that the high-voltage system will not come on at all.
Possible causes
- CommonWiring or connector fault in the shutdown circuit
- CommonLow 12 volt battery voltage - the small battery, not the traction battery
- PossibleFailed contactor or its control circuit
- PossibleHigh-voltage interlock loop opened by a disturbed service plug or cover
- PossibleFailed battery management module
What you might notice
- Vehicle will not power up or will not move
- High-voltage system warning message
- Vehicle will not charge
- Hybrid running on the engine alone
- Warning lights for the electric drive system
What to check, in order
- Check the 12 volt battery first. On hybrids and electric vehicles a weak 12 volt battery causes a scatter of high-voltage system codes and strands people who assume the expensive traction battery is at fault.
- Check whether a service disconnect plug or high-voltage cover has been disturbed. The interlock loop is designed to shut the system down when one is loose.
- Read all codes - a battery management module code alongside this one changes the diagnosis.
- Read the manufacturer's high-voltage service procedure before going any further.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx