P0655 — Engine-hot warning-lamp output — circuit fault

The monitor for engine-hot warning-lamp output reports a problem in the named circuit; an open, short or particular failed part is not established by the label alone. The output circuit is not the same as the original sensor input. A warning-lamp circuit fault alone does not confirm the physical condition represented by that lamp.

Affected system: Instrument and warning-signal outputs

Symptoms

• Warning light may illuminate
• Related system function may be impaired
• Vehicle-specific symptoms vary

Possible causes

• Implausible sensor or switch signal, poor ground, connector corrosion, or wiring damage
• Related wiring, connector, power or ground fault
• Vehicle-specific mechanical or control issue

What to check

• Record stored and pending codes and freeze-frame data
• Compare the named sensor or switch signal with actual operating conditions; inspect the connector, reference supply, ground and harness.
• Confirm measured values against the vehicle service information
• Retest under the conditions that set the code
• Compare the named sensor or switch signal with actual operating conditions; inspect the connector, reference supply, ground and harness.
• Repair the verified cause and confirm the code does not return

Also written as: P0655-00, P065500, PO655 (some scan tools add the fault-type byte, e.g. -00).