P0A27 code meaning
Hybrid/EV Battery Power Off Circuit
Powertrain system Generic code P0Axx codes Check engine light
What P0A27 means
P0A27 covers the circuit that tells the high-voltage battery to drop off the bus, i.e. the command path that opens the main contactors at key-off, after a fault or after a crash signal. Patents describe such a path as a dedicated hardware line in addition to CAN, so the contactors open within milliseconds. The code sets when commanded and actual state disagree. Honda lists P0A27 as High Voltage Contactor Stays Activated on the 2012-15 Civic Hybrid, where it is one of the codes that call for replacing the motor power inverter. P0A28 and P0A29 are the low and high voltage faults of the same line. The driver may see a hybrid warning and the car may refuse to start or power down.
P0A27 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0A27
- Hybrid system warning or check engine light
- Vehicle will not enter ready mode or shuts down while driving
- High-voltage system does not power down after key-off
Common causes of P0A27
- Most likelyContactor or its driver does not release when power-off is commanded
- PossibleInternal fault in the inverter/power unit that controls the contactors (Honda Civic Hybrid)
- PossibleDamaged wiring or loose terminal on the hardwired power-off line
- Less likelyCrash or emergency shutdown signal stored or still active
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 circuitMain contactorsBms
What each part of P0A27 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. |
| 27 | The exact fault in that area. |
What to do next
- Note P0A27 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 P0A27
What does P0A27 mean?
P0A27 means "Hybrid/EV Battery Power Off Circuit". P0A27 covers the circuit that tells the high-voltage battery to drop off the bus, i.e. It is a generic code, so it means the same on every make.
Is it safe to drive with P0A27?
Drive gently and only to a workshop. With P0A27 the car can go into limp mode (reduced power) to protect itself.
Will P0A27 fail an emissions test?
Yes, it can. P0A27 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 P0A27 to fix?
Difficulty: workshop only. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will P0A27 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.