P0655: Engine Hot Lamp Output Control Circuit

What does P0655 mean?

The engine module switches this hard-wired output with its own driver and checks the circuit electrically (open, short to ground or voltage) – it cannot see whether the lamp lights; on CAN-based cars such faults appear as U codes. P0655 concerns the engine hot or coolant warning lamp that the engine module switches by wire from the coolant temperature signal. CARB links overtemperature protection strategies to this lamp: a protective reaction that only starts after the hot lamp lights needs no MIL. No manufacturer document available to us uses this code; the description follows CARB and the component. If the circuit fails, the driver may not be warned of overheating – check it promptly even though the check engine light usually stays off. Actual overheating is P0217; the coolant sensor circuit is P0117/P0118.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Temperature warning lamp does not light at bulb check or when overheating
• Warning lamp stays on without overheating
• Code stored, check engine light depending on the maker

Common causes

• High Wire or connector between module and receiver open, corroded or shorted
• Medium Bulb/LED or instrument cluster faulty
• Medium Lamp supply missing (fuse)
• Low Output driver in the module faulty

Likelihood is a general estimate across vehicles; your make and model may differ.