P0A05 Motor Electronics Coolant Pump Control Circuit/Open

P0A05 indicates an open or general fault in the motor electronics coolant pump control circuit. The controller cannot command or monitor pump operation correctly.

Code status

Needs verification

Not yet verified against SAE J2012_202509 / J2012DA. Treat unverified rows as a lookup aid, not repair authority.

System: Hybrid / EV
Scope: iso-sae-controlled-p0
Standard: SAE J2012 / ISO 15031-6
Source: legacy-import

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not operate the vehicle under load if the motor electronics coolant pump may be inoperative.

Useful checks before replacing parts

Check pump command, pump speed feedback where available, fuse feed, relay or module output, coolant temperature, inverter temperature, and freeze-frame load.
Inspect pump connector terminals, power and ground circuits, control wiring, coolant intrusion, harness damage, pump blockage, and cooling system bleed condition.
Command the pump with a scan tool where supported and verify voltage, current draw, coolant movement, and temperature response.

Related OBD-II codes

These nearby hybrid / ev entries can help compare wording and fault area. They may share the same verification status as the source database.