The Engine Control Module (ECM) detects the following conditions:

•For C7 engines that are not in emergency vehicles, the engine coolant temperature is at least 111° C (232° F) for more than four seconds.
•For C7 emergency vehicles and for C9 vehicles, the engine coolant temperature is at least 116° C (241° F) for more than four seconds.
•For C9 emergency vehicles with automatic transmissions, the engine coolant temperature is at least 121° C (250° F) for more than four seconds.
•The engine has been running more than 30 seconds.

Note: This diagnostic code represents a critical event. This diagnostic code does not represent an electronic system fault.

Possible Causes:

1) Low Coolant level
2) Wiring at either ther coolant level sensor, ECM, or in between
3) ECM Failure