What is a coolant temperature sensor?
A coolant temperature sensor works to measure the overall temperature of your vehicle’s coolant. Once the temperature sensor or switch has a reading, it passes this information along to the engine control module (ECM) or engine control unit (ECU). The ECM or ECU uses that information to help it control a number of things, including:
Fuel injection and mixture
Dashboard temperature display
When should I replace the coolant temperature sensor in my car?
Coolant temperature sensors/switches should be replaced every 100,000 miles, but routinely inspected to ensure there is no damage or corrosion present. Common symptoms of a faulty coolant temperature switch or sensor are:
Engine overheating: As your car’s cooling system is designed to intake and expel intense heat from your engine, it’s important that the temperature of your coolant is correct. Inaccurate readings can trick the ECU into believing the engine isn’t hot when it is, leading to overheating.
Check engine light: Faulty sensors can also ignite your dashboard lights—specifically the check engine light. Sometimes, an error code can also appear, hinting at a potential malfunctioning coolant temperature sensor.
Black exhaust smoke: The coolant temperature sensor not only helps cool your car, but also aids the engine in deciding fuel-air mixture. Faulty sensors can result in overly rich fuel-air mixtures, causing black exhaust to come out of your pipes.
Inconsistent temperature reading: This is one of the leading symptoms of a broken coolant temperature sensor. If you notice a fluctuating or erratic reading from your temperature gauge while driving, it’s likely the result of a coolant temperature sensor problem.
Difficulty starting car: Since the coolant temperature switch also works with the ECU, if a damaged coolant sensor is leading to a high fuel-air mixture, you may have trouble cranking your vehicle’s engine.
How often should a coolant temperature sensor/switch be replaced?
Your car’s coolant temperature sensor or switch should be replaced every 100,000 miles to ensure that your engine is operating at the accurate temperature. However, this varies based on the vehicle you drive—Volkswagen coolant temp sensors experience failure more often, for instance, so you may need to replace the sensor more frequently if you drive one.
Consult your owner’s manual and mechanic to determine when to conduct your vehicle’s routine coolant temperature replacement.
Can I replace my coolant temperature sensor myself?
Yes, you can replace your coolant temperature sensor on your own. This type of replacement requires a mid-level knowledge of mechanical operations—but it is relatively simple to complete. If you’re unfamiliar with car repairs, or unsure of your ability to complete a coolant temperature sensor replacement on your own, contact a licensed mechanic.