Where is the coolant temperature sensor located in the 2003 Corolla?

The coolant temperature sensor on a 2003 Toyota Corolla is located on the driver side of the engine just behind the distributor. To get to it You will need to remove the airboxAnd the throttle body. There is an electrical connector on the end of it that needs to be unclipped and then use a 19-millimeter wrench to unscrew it. Once the sensor is broken free, You can remove it by hand. When installing the new sensor, tighten by hand at first to prevent cross threading it and snug it down with the wrench. The sensor detects the temperature of the coolant inside the engine and sends the data to the computer. If the sensor goes bad, it will normally send the fault code P0128 to the OBD-II.