P0655 Engine Hot Lamp Output Control Circuit

P0655 indicates an engine hot lamp output control circuit problem. The controller cannot command or monitor the over-temperature warning indicator correctly.

Code details

Generic OBD-II · P0

System: Computer
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

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 ignore true overheating while diagnosing the engine hot lamp control circuit.

Symptoms of P0655

Check-engine light, sometimes with several unrelated codes at once.
Warning lights, a no-start, or intermittent electrical faults.
Communication or module-reset problems on a scan tool.

Common causes of P0655

Low battery voltage, poor grounds, corroded connectors, or blown fuses.
Wiring or network (CAN bus) faults between modules.
A module software/programming issue, or rarely a failed controller.

Useful checks before replacing parts

Check engine hot lamp command, coolant temperature data, cluster warning status, fan operation, freeze-frame data, and related coolant temperature codes.
Inspect lamp control wiring, cluster connector, CAN warning messages, module power and ground, coolant sensor plausibility, and warning lamp driver output.
Verify the warning indicator can be commanded and that coolant temperature data supports or contradicts the warning.

Related OBD-II codes

These nearby computer entries can help compare wording and pin down the fault area.