What it means
The control module detects that drive motor A performance is outside its expected range.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Drive motor A is one of the vehicle's hybrid or electric traction motors, controlled through power electronics that regulate high-voltage current. The control module compares motor A's requested and reported performance, and sets P0A90 when that performance falls outside the expected range; the code identifies motor A, but does not by itself prove the motor has failed.
Common causes
Most likely first.
- Drive motor fault
- Motor wiring or high-voltage connection fault
- Motor control or inverter fault
Symptoms
- EV/hybrid system warning light on
- Reduced motor power or torque
- Possible limp mode or vehicle shutdown
How to diagnose it
- Read freeze-frame data and hybrid control live data for motor A, including requested versus actual torque or speed where available, to establish when the mismatch occurs.
- Check for related motor, inverter, battery, and high-voltage system codes that may identify a shared cause or a fault affecting motor A.
- With the vehicle powered down according to the manufacturer's safety procedure, visually inspect accessible motor A wiring and high-voltage connectors for damage, contamination, or signs of overheating.
- Have motor A's control signals, position or speed feedback, and associated wiring tested against the manufacturer's diagnostic procedure.
- If wiring and feedback checks pass, test motor A and its inverter channel using the vehicle-specific hybrid diagnostics.
Common fixes
- Repair damaged motor A wiring or connector faults identified by inspection and testing.
- Correct a related inverter, power supply, or control fault that is disrupting motor A operation.
- Repair or replace drive motor A if testing confirms an internal motor fault.
- Replace or repair the motor A inverter section if diagnostics isolate the fault there.
Can I keep driving?
Avoid hard acceleration and long trips; reduced torque or limp mode can make merging and climbing unsafe, and the vehicle may shut down. Stop in a safe place if propulsion becomes unreliable, and have high-voltage diagnosis performed by a suitably trained technician.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.