P0A31 code meaning
Drive Motor B Temperature Sensor Circuit Range/Performance
Powertrain system Generic code P0Axx codes Check engine light
What P0A31 means
P0A31 checks whether the motor B temperature reading makes sense, typically after a long rest when all parts should be close to the same temperature. GM compares it with other temperatures: the 2011 tables flag a gap above 20 °C to the average of power-electronics coolant and transmission fluid after 6 h without propulsion (Type A); the 2013 two-mode trucks allow 28 °C against the inverter module after 360 min key-off (Type B, two trips). Mitsubishi (2023 Outlander PHEV rear motor) compares two coil sensors after 5,400 s soak and sets it at 13 °C difference. P0A32 and P0A33 cover hard circuit faults; P0A35 is only judged while this test passes. Expect a hybrid warning and limited electric drive.
P0A31 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 6 hours
- Clears after repairAfter a drive cycle
Symptoms of P0A31
- Hybrid warning light after a cold start
- Motor B temperature differs clearly from other temperatures after a long rest
- Electric drive limited as a precaution
Common causes of P0A31
- Most likelyMotor B thermistor reading drifted out of tolerance
- PossibleCorroded terminals adding resistance in the sensor circuit
- Less likelyComparison sensor (inverter, coolant or fluid temperature) is wrong
- Less likelyUneven cooling of the drive unit, e.g. low fluid level
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Drive motor b temp sensorWiring harnessHybrid control module
What each part of P0A31 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. |
| 31 | The exact fault in that area. |
What to do next
- Note P0A31 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 P0A31
What does P0A31 mean?
P0A31 means "Drive Motor B Temperature Sensor Circuit Range/Performance". P0A31 checks whether the motor B temperature reading makes sense, typically after a long rest when all parts should be close to the same temperature. It is a generic code, so it means the same on every make.
Is it safe to drive with P0A31?
Drive gently and only to a workshop. With P0A31 the car can go into limp mode (reduced power) to protect itself.
Will P0A31 fail an emissions test?
Yes, it can. P0A31 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 P0A31 to fix?
Difficulty: workshop only. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will P0A31 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.