P0A90 code meaning
Drive Motor A Performance
Powertrain system Generic code P0Axx codes Check engine light
What P0A90 means
P0A90 reports that electric drive motor A does not behave as commanded. In GM's eAssist mild hybrid the motor/generator is belt-driven from the crankshaft, so GM uses P0A90 to detect a slipping or broken belt: the motor speed is compared with the engine speed. In 2013 a difference above 1000 rpm for 1.5 s, or repeated smaller slips above 500 rpm on two key cycles, set it; the 2016 tables use more than 1500 rpm for about 5.6 s or repeated 1000 rpm slip events. GM rates it Type A, MIL on the first trip. In full hybrids the generic definition applies to speed or torque deviations of the traction motor. P0A91 is the equivalent for motor B, P0A92 for the generator.
P0A90 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0A90
- MIL and hybrid system warning
- Belt squeal or auto-stop/start not working
- Reduced electric assist or limp mode
Common causes of P0A90
- Most likelySlipping, worn or broken drive belt on belt-driven motor/generators
- PossibleFaulty belt tensioner or contamination on the belt
- PossibleMotor, position sensor or inverter fault in full hybrids
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Drive motor a
What each part of P0A90 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. |
| 90 | The exact fault in that area. |
What to do next
- Note P0A90 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 P0A90
What does P0A90 mean?
P0A90 means "Drive Motor A Performance". P0A90 reports that electric drive motor A does not behave as commanded. It is a generic code, so it means the same on every make.
Is it safe to drive with P0A90?
Drive gently and only to a workshop. With P0A90 the car can go into limp mode (reduced power) to protect itself.
Will P0A90 fail an emissions test?
Yes, it can. P0A90 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 P0A90 to fix?
Difficulty: medium. A typical repair takes 0.5 to 6 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0A90 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.