What Does P0655 Mean?
The engine hot warning lamp output circuit has a malfunction. The ECM has detected that the circuit it uses to control the engine overheating warning light on the instrument cluster is not working properly. The driver may not be alerted if the engine overheats, which is a significant safety concern. The lamp may stay on continuously, not illuminate during the bulb check, or fail to activate when coolant temperature is excessive.
Common Causes
30%
Burned-out warning lamp bulb or failed LED in the instrument cluster
25%
Open or shorted wiring between ECM and instrument cluster for the hot lamp circuit
20%
ECM internal lamp driver failure for the engine hot warning output
15%
Faulty instrument cluster circuit board (lamp driver section)
10%
Corroded ground connection for the warning lamp circuit
Diagnostic Steps
1
Turn the ignition to ON (engine off) and verify the engine hot lamp illuminates during the bulb check sequence. If it does not, the lamp or circuit is faulty.
2
At the instrument cluster connector, back-probe the engine hot lamp control wire. Use a scan tool to monitor coolant temperature and, if possible, command the lamp on. Verify the control signal toggles properly.
3
If the ECM signal is present at the cluster but the lamp does not respond, test the lamp by applying 12V or ground directly to the appropriate pin. If the lamp still does not work, the cluster needs repair.
4
If no signal is present at the cluster, trace the wire from ECM to cluster. Check for continuity and shorts to ground or B+.
5
If wiring is good and the ECM cannot command the lamp, the ECM's internal hot lamp driver has failed. This typically requires ECM replacement.
Estimated Repair Cost
$50 - $600
Parts + labor, varies by vehicle and location
The engine hot warning lamp output circuit has a malfunction. The ECM has detected that the circuit it uses to control the engine overheating warning light on the instrument cluster is not working properly. The driver may not be alerted if the engine overheats, which is a significant safety concern....
The most common cause of P0655 (Engine Hot Lamp Output Control Circuit Malfunction) is: Burned-out warning lamp bulb or failed LED in the instrument cluster
Typical repair costs for P0655 range from $50 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This is a safety concern because you will not be alerted if the engine overheats. Overheating without warning can cause catastrophic engine damage (warped heads, blown head gasket, seized engine). Monitor the coolant temperature gauge closely while driving and repair this promptly. Consider using a scan tool app to provide a secondary temperature alert.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0655 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Cooling / Warning System
Difficulty
Type
Generic (SAE)
Recommended Tools
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