P0655 Engine Hot Lamp Output Control Circuit Malfunction
OBD-II Trouble Code Technical Description
Engine Hot Lamp Output Control Circuit Malfunction
What does that mean?
This is a generic diagnostic trouble code (DTC) and applies to many OBD-II vehicles (1996-newer). That may include but is not limited to vehicles from Alfa Romeo, Peugeot, MG, Dodge, Buick, Cadillac, Chevrolet, Ford, GMC, Opel, etc. Although generic, the exact repair steps may vary depending on year, make, model, and powertrain configuration.
A stored code P0655 means that the powertrain control module (PCM), or one of the other related controllers, has detected a discrepancy in the engine hot lamp output control circuit.
The engine hot lamp is designed to provide the driver with a visual warning lamp when the engine is overheating. The engine hot lamp is integral to the instrument panel. The PCM receives a signal from the engine coolant temperature sensor. This signal allows the PCM to monitor engine coolant temperature whenever the engine is running or the ignition switch is in the ON position. This data is used primarily for calculating engine fuel delivery and ignition timing strategy and then output to the engine hot lamp and/or instrument panel controller. It may also be output to other controllers. For instance, the engine hot lamp control circuit may be output to the climate control module so that the air conditioning compressor can be disabled if the engine overheats.
If a problem is detected in monitoring the engine hot lamp output control circuit, a code P0655 will be stored and a malfunction indicator lamp (MIL) may be illuminated.
Typical simple gauges:
What is the severity of this DTC?
A P0655 should be categorized as severe because it could result in numerous drivability issues as well as fail to warn the driver in the event of engine overheating.
What are some of the symptoms of the code?
Symptoms of a P0655 trouble code may include:
Engine drivability issues Inoperative engine hot lamp Engine hot lamp is illuminated constantlyWhat are some of the common causes of the code?
Causes for this code may include:
Open or shorted circuit between the PCM and the instrument panel or other controllers PCM programming error Faulty controller or PCMWhat are some P0655 troubleshooting steps?
If there are engine overtemp codes or engine temperature sensor codes present; diagnose and repair those before attempting to diagnose a stored P0655.
Make sure that the engine is filled with the appropriate coolant and not overheating.
Consult your vehicle information source for technical service bulletins (TSB) that replicate the code stored, vehicle (year, make, model, and engine), and symptoms exhibited. If you find the appropriate TSB, it may yield helpful diagnostic information.
A diagnostic scanner and a digital volt/ohmmeter will be necessary to accurately diagnose a code P0655. A reliable source of vehicle information will also be required.
Begin by connecting the scanner to the vehicle diagnostic port and retrieving all stored codes and freeze frame data. You will want to write this information down, just in case the code proves to be an intermittent one.
After recording all pertinent information, clear the codes and test drive the vehicle (if possible) until the code is reset or the PCM enters readiness mode.
If the PCM enters readiness mode, the code is intermittent and will be even more difficult to diagnose. The condition, which caused the P0655 to be stored, may need to worsen before an accurate diagnosis can be reached. On the other hand, if the code fails to reset and there are no drivability symptoms exhibited, the vehicle can be operated normally.
If the P0655 is immediately reset, proceed with a visual inspection of system related wiring and connecto
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