Genuine 2007 BMW 335i Coolant Temperature Sensor

2007 BMW 335i Coolant Temperature Sensor Parts Questions & Experts Answers

• Q:

  What is the function and replacement process of the coolant temperature sensor in the N55 six-cylinder engine on the 2007 BMW 335i?

  Posted by Mack T.

  A:

  The ECT sensor is the negative temperature coefficient (NTC) type; in this case resistance varies inversely to the temperature, in this case the engine coolant temperature. The ECM is designed to change ignition time and A/F mixture according to the coolant temp and it takes 5-volt reference voltage. Voltage drop across the subtense is affected by cooler temperature, therefore changes in the same affects its value. If there is a failure in the ECT sensor input or if the input is implausible, the malfunction indicator light or MIL turns on if OBD II fault criteria have been met and the ECM uses an 80°C (176°F) default value and conservatively sets the ignition timing at basic level. ECT sensor is installed at the front of the cylinder head. Instead, be sure that the engine is cooled down, undo the fastener and the line and be very keen not to spill any of the dripping fluids. Locate the electrical connector just below the thermostat housing and unplug it then remove the bolts that secures the ECT sensor to the cylinder head, you may lose some coolant in process. At shutdown during installation, or inding, replace a copper sealing washer, examine the O-rings on the coolant line, and replenish any shed coolant. After reinstalling check for the fault codes and clear ECM memory.

  Answered by BMW Parts Specialist Brandon / Sep 27, 2024