* Low coolant level: If the coolant level is too low, the coolant pump may not be able to circulate enough coolant through the engine, resulting in insufficient coolant temperature.
* Faulty thermostat: The thermostat is responsible for regulating the flow of coolant through the engine. If the thermostat is stuck open, too much coolant will flow through the engine, resulting in insufficient coolant temperature. If the thermostat is stuck closed, not enough coolant will flow through the engine, resulting in overheating.
* Faulty coolant temperature sensor: The coolant temperature sensor is responsible for sending the engine coolant temperature signal to the engine control module (ECM). If the coolant temperature sensor is faulty, the ECM may not receive the correct coolant temperature signal, resulting in insufficient coolant temperature.
* Faulty ECM: The ECM is responsible for controlling the fuel injection and ignition timing based on the engine coolant temperature. If the ECM is faulty, it may not be able to correctly control the fuel injection and ignition timing, resulting in insufficient coolant temperature.
To diagnose the cause of insufficient coolant temperature for closed loop fuel control, you will need to check the coolant level, inspect the thermostat, test the coolant temperature sensor, and scan for any trouble codes.
