Coolant Temp. Sensors, Replacement Coolant Temperature Sensors
The coolant temperature sensor detects the temperature of the coolant and feeds that information to the main computer of the car. This information is used to help the engine run efficiently while it is warming up. In older models, the choke performed this function, ensuring that the fuel/air mixture was rich until the engine was at proper operating temperature. Now, this is handled by the engine control unit. The coolant temperature sensor replaces the need for the choke to control this function. Checking for a faulty coolant temperature sensor is simple and will diagnose the problem quickly. The voltage output of the sensor, also called ECT for engine coolant temperature, must be checked as the engine is warming up. Voltage should measure 0.8-1.2 volts. If it is higher than this, the sensor will continue to tell the computer that the engine is cold even when it is nearly at the correct temperature. This causes the engine to run too rich and can disrupt timing.