A control system for an engine or exhaust system includes a sensor that detects an exhaust gas temperature and a sensor that detects an exhaust coolant temperature. The sensors communicate with a controller. Based upon the output from the sensors, the controller determines whether each sensor is functioning properly and whether the cooling system is functioning properly. In the event of a malfunction of a sensor or the cooling system, an alarm is issued and the speed or operation of the engine is altered. In addition, if the controller detects a problem with the coolant system based upon coolant temperature or with the coolant temperature sensor, then the controller disables a starter motor such that the engine cannot be restarted without resetting the starter motor. The start motor can be disabled through a relay and the relay can be reset manually or automatically after a preset period of time.