BMW 13621433077 Coolant Temperature Sensor

A BMW dealer or specialist should test the radiator outlet thermostatic switch, located in the radiator lower hose. It should only be removed when the engine and radiator are cold. Disconnect the battery cable before removing the switch and use a plug to prevent foreign matter from entering the radiator. The coolant temperature sensor is on the cylinder head's front side. Remove the air intake duct and disconnect the wiring before unscrewing the sensor. Apply sealant to the threads before reinstallation. The coolant level sensor is in the coolant expansion tank base. Disconnect the electrical connector and remove the bolts to access the sensor. Rotate it counterclockwise for removal. Installation is the reverse of removal.

The PCM adjusts the intake air/fuel mixture based on input from the engine coolant temperature sensor and other sensors. To replace the sensor, first disconnect the electrical connector at the ECT. Next, unscrew the sensor by means of a wrench. When installing the new sensor, follow same steps as removal but make sure to use a new copper washer. After installation run engine and check for any coolant leakage. Finally, use a scan tool to look for any Diagnostic Trouble Codes (DTCs).

A BMW dealer or specialist should test the radiator outlet thermostatic switch, located in the radiator lower hose. It should only be removed when the engine and radiator are cold. Disconnect the battery cable before removing the switch and use a plug to prevent foreign matter from entering the radiator. The coolant temperature sensor is on the cylinder head's front side. Remove the air intake duct and disconnect the wiring before unscrewing the sensor. Apply sealant to the threads before reinstallation. The coolant level sensor is in the coolant expansion tank base. Disconnect the electrical connector and remove the bolts to access the sensor. Rotate it counterclockwise for removal. Installation is the reverse of removal.

The engine coolant temperature (ECT) sensor is an NTC (negative temperature coefficient) sensor, which means that as the coolant temperature rises, the resistance through the sensor decreases. The ECM adjusts ignition timing and air/fuel mixture based on the engine coolant temperature, receiving a 5-volt reference voltage. The voltage drop across the sensor changes with variations in coolant temperature and sensor resistance. If the ECT sensor input is faulty or implausible, the MIL illuminates when OBD II fault criteria are exceeded, prompting the ECM to assume a substitute value of 80 degrees Celsius/176 degrees Fahrenheit to maintain engine operation, with ignition timing set to a conservative basic setting. The ECT sensor is located at the left front of the engine near the oil cooler. To replace it, ensure the engine is fully cooled, then disconnect the ECT sensor connector and unscrew the sensor from the cylinder head, being prepared to catch a small amount of coolant. Installation involves reversing the removal process, using a new copper sealing washer, and replacing any lost coolant. After reinstalling, check and clear fault codes from the ECM memory.

The ECT sensor is a two-pin temperature sensor that supplies the coolant temperature to the ECM and the instrument cluster. It works in a similar way to an NTC (negative temperature coefficient) sensor; its resistance drops as the temperature of the coolant increases. The ECM changes ignition timing and air/fuel mixture with regard to the water temp; the sensor receives a 5-volt reference voltage, the voltage drop across the sensor varying with water temperature. If ECT sensor input is out of range, or unrealistic expected by the ECM, the MIL comes on whenever the OBD II fault criteria is met, and to ensure the engine runs, the ECM sets an assumed ECT value at 80 degree Celsius plus its offset 176 degrees f, while setting ignition timing to a conservative basic setting. It is mounted at the rear of the engine, to the left of cylinder 6, beneath the intake port and above the intake manifold. It is located under the intake manifold and thus to get to it, the manifold must be taken off after the engine has cooled. The ECT sensor connector has to be removed to eliminate the connection, and the sensor should then be unscrewed from the cylinder head, be careful as there will be some lose coolant. For reinstallation a new copper sealing washer has to be used, lost coolant has to be replenished and the DTC had to be checked and then cleared of its memory by resetting the ECM.

The coolant temperature sensor should be tested and removed by a qualified repair shop.

If the ECT sensor input is faulty or implausible, the MIL (Malfunction Indicator Lamp) illuminates, prompting the ECM to assume a substitute value of 80°C/176°F to maintain engine operation, while setting ignition timing to a conservatively safe basic level.

The sensor is positioned in the lower radiator hose on the right side of the radiator.

The first step is to detach the electrical connector from the sensor.