Coolant Temp Sensor Service Video

The coolant temperature sensor tells your engine computer how hot the coolant is. That reading sets fuel mixture, ignition timing, and radiator fan behavior. This video shows where the sensor sits and compares a good scan-tool reading with a failing sensor's data at cold start and full temperature.

The sensor is a thermistor threaded into the block or a coolant passage near the thermostat housing. Its resistance changes as coolant heats up, and the computer reads that as a voltage signal. A dirty connector or aged thermistor sends the wrong reading, so the engine responds to a temperature that is not real.

A check engine light with a P0115 to P0119 code is the clearest flag, along with hard cold starts and rough idle until warm-up. An erratic gauge or radiator fans cycling at the wrong times point the same way. If the gauge climbs while driving, start with radiator inspection and repair, since the cooling system itself may be at fault.

Replacement starts with scan-tool readings at cold and hot engine states, compared with the manufacturer's expected curve. If the sensor has failed, the system is partly drained, and a new sensor goes in at the correct torque. The system is then refilled, bled of air, and the data stream is checked again.

Affordable Automotive Services scans live data before touching a wrench. A code that points at the sensor can also mean a wiring fault, a bad ground, or a thermostat stuck open. Sensor testing is part of our cooling system repair services, which cover the radiator, hoses, thermostat, and water pump.

Dry heat and dust around Grant County corrode the connector at the sensor pigtail. That skews the voltage signal long before the sensor fails, so the connector is cleaned and checked on every test. Every repair is backed by our 5-year / 50,000-mile parts and labor warranty.

Call Affordable Automotive Services at (509) 764-0000 to have your coolant temp sensor tested. We’re a short drive from Ephrata, Quincy, and Othello for auto repair in Moses Lake. Plenty of drivers from those towns already trust us with their cooling systems.