Powertrain, generic · Hybrid propulsion

P0A90 Drive Motor A Performance

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Slipping, worn or broken drive belt on belt-driven motor/generators
Faulty belt tensioner or contamination on the belt
Motor, position sensor or inverter fault in full hybrids

Symptoms

  • MIL and hybrid system warning
  • Belt squeal or auto-stop/start not working
  • Reduced electric assist or limp mode

Repair estimate

DifficultyMediumDIY possible
Parts and labour€60–3,000
Time0.5–6 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

drive motor a

Related codes

P0A91P0A92P0A3FP0A78P0C19

References: gsi.ext.gm.com, gsi.ext.gm.com.