Faulty motor position sensor (resolver) or its wiring; Damaged or corroded wiring and connectors between the motor and inverter; Internal motor failure such as shorted windings or damaged bearings; Inverter or motor control module malfunction; Low or contaminated hybrid transaxle fluid affecting motor cooling and lubrication; Software calibration issues in the powertrain control module

DTC codes / P0Axx · Hybrid propulsion / P0A90

P0A90Drive Motor A Performance

Q: What does code P0A90 mean?

Drive Motor A Performance. P0A90 indicates that the powertrain control module has detected a performance problem with Drive Motor A, which is the primary traction motor in a hybrid or electric vehicle. The computer monitors the motor's speed, current draw, and torque output against expected values and sets this code when the actual performance falls outside the acceptable range.

P0A90 indicates that the powertrain control module has detected a performance problem with Drive Motor A, which is the primary traction motor in a hybrid or electric vehicle. The computer monitors the motor's speed, current draw, and torque output against expected values and sets this code when the actual performance falls outside the acceptable range.

SystemPowertrain

Code typeGeneric (all makes)

SeverityHigh

Fix difficultyProfessional

AreaHybrid propulsion

Symptoms you may notice

Illumination of the check engine light or hybrid system warning light, often with no other noticeable symptoms
Reduced power or a limp-home mode that limits vehicle speed
Hesitation or shuddering during acceleration
Unusual noises such as whining or grinding from the motor area
The vehicle may fail to start or move in electric-only mode
In some cases, the engine may run continuously or the hybrid system may shut down

Common causes, most likely first

Faulty motor position sensor (resolver) or its wiring
Damaged or corroded wiring and connectors between the motor and inverter
Internal motor failure such as shorted windings or damaged bearings
Inverter or motor control module malfunction
Low or contaminated hybrid transaxle fluid affecting motor cooling and lubrication
Software calibration issues in the powertrain control module

How to diagnose and fix it

Scan all modules for stored codes and freeze-frame data to confirm P0A90 and identify related faults
Inspect the motor wiring harness and connectors for damage, corrosion, or loose pins
Check the hybrid transaxle fluid level and condition, looking for metal debris or contamination
Test the motor position sensor (resolver) signal with an oscilloscope or manufacturer-specific diagnostic tool
Perform a motor performance test using the scan tool to compare actual versus commanded torque and current
If sensor or wiring faults are ruled out, follow the manufacturer's diagnostic flow for internal motor or inverter testing
Reprogram or update the powertrain control module if a software calibration bulletin applies

What a P0A90 code often hides

A weak or failing 12-volt auxiliary battery can cause erratic motor control module behavior and set P0A90 without any actual motor fault.
The motor position sensor is a common failure point that is often misdiagnosed as an internal motor failure, leading to unnecessary replacement of the entire motor assembly.
Debris or sludge in the hybrid transaxle fluid can block cooling passages and cause the motor to overheat, triggering a performance code before any permanent damage occurs.
Some vehicles set P0A90 when the inverter coolant pump fails, because the motor and inverter share a cooling circuit and overheating degrades performance.
After any repair, the motor resolver offset may need to be relearned with a scan tool, or the code will reset immediately even though the fault is fixed.

Can I keep driving with P0A90?

Driving with P0A90 is not recommended because the vehicle may enter a reduced-power mode without warning, and continued operation can lead to permanent motor or inverter damage. Have the vehicle towed to a qualified repair facility if it is not already in limp mode.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.