Code Definition

P0A90 (239) — Drive motor A performance

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Toyota

About P0A90

P0A90 is a generic (obd-ii standard) powertrain diagnostic trouble code recorded for Toyota vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P0A90 is stored, the module has detected a plausibility fault — the measured value is in the electrical range but is not consistent with expected operating behaviour.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P0A90 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

On Toyota and Lexus hybrids the hybrid vehicle control ECU monitors Motor Generator 2 (MG2), the main traction motor referred to as Drive Motor A, which sits in the hybrid transaxle and is driven by the inverter. DTC P0A90 with this manufacturer subcode sets when the ECU detects an MG2 performance problem during driving, where commanded torque or rotational speed does not match the actual feedback from the motor, inverter, or MG2 resolver beyond a calibrated threshold under load. The cause can lie in the MG2 windings, the inverter assembly, the MG2 resolver and its circuit, or the high voltage...

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