One of the common problems is when the sensor has poor connection inside or in the connector or in the wiring harness. If the signal from the sensor is missing, or it is outside of the expected range, the PCM turns on the Check Engine light and stores the related trouble code in its memory. Based on this signal, the PCM adjusts the engine performance and operates the electric radiator fans when the temperature reaches a pre-determined level. The PCM supplies a reference voltage (typically 5 Volt) and constantly monitors the ECT sensor signal. In some cases, this may help prevent overheating.Īn ECT sensor is connected to the main computer (powertrain control module or PCM). This allows the CHT sensor to measure the temperature of the engine correctly even with loss of coolant. The CHT sensor (see the photo) works the same way, but it measures the temperature of the cylinder head metal and is not immersed in coolant. Some cars use a cylinder head temperature or CHT sensor instead of, or in addition to the ECT sensor. Steps to diagnoseĮCT sensor is connected to the engine computer or PCMĪ second coolant temperature sensor could be installed in another part of the engine, or in the radiator. Signs of automatic transmission problems.How to check the engine when buying a used car.How to get the best deal on a used car?.Buying a Used Car: 10 Common Mistakes to Avoid.
