Symptoms of Bad Coolant Temp Sensor

The coolant temperature sensor is a crucial component of your vehicle’s engine. That helps regulate the engine’s temperature. A faulty coolant temperature sensor can cause a variety of symptoms that can negatively affect your vehicle’s performance and fuel economy. Some common symptoms of bad coolant temp sensor include the engine running hot and poor fuel economy.

If you notice any of these symptoms, it’s important to have your vehicle inspected by a qualified mechanic to diagnose and address the issue promptly. However, before you take your vehicle to the mechanic, what are the visible symptoms you should look for?

9 Symptoms of Bad Coolant Temp Sensor

The coolant temperature sensor is also known as the engine coolant temperature (ECT) sensor. It plays a crucial role in the proper functioning of your vehicle’s engine. It monitors the temperature of the engine coolant and sends that information to the engine control module (ECM). However, just to help regulate the engine’s operating temperature. A malfunctioning coolant temperature sensor can cause a range of problems, so it’s important to be aware of the following nine symptoms of a bad coolant temp sensor:

Engine Running Hot:

If your car engine is overheating, it could be due to a faulty coolant temperature sensor. It can cause a range of issues, from reduced performance to engine damage, if left untreated.

Poor Fuel Economy:

If the coolant temperature sensor sends inaccurate readings to the ECM, it can result in poor fuel economy, as the engine may be running too rich or too lean.

Rough Idle:

A bad coolant temperature sensor can also cause a rough idle, as the engine may run too cold or hot, causing it to struggle to maintain a steady idle speed.

Engine Stalling:

A faulty coolant temperature sensor can cause the engine to stall or shut down unexpectedly, as the ECM may receive inaccurate temperature readings and adjust the engine’s performance accordingly.

Check Engine Light:

A malfunctioning coolant temperature sensor can trigger the check engine light to come on, as the ECM may detect an issue with the sensor’s readings.

Decreased Performance:

A bad coolant temperature sensor can cause decreased performance, as the ECM may adjust the engine’s performance based on inaccurate temperature readings.

Increased Emissions:

If the engine is running too rich or too lean due to a faulty coolant temperature sensor, it can result in increased emissions, which can cause your vehicle to fail an emissions test.

Poor Heater Performance:

If the coolant temperature sensor sends inaccurate readings to the ECM, it can also affect the performance of your vehicle’s heater, as it relies on the engine’s coolant to provide heat.

If you notice any of these symptoms, it’s important to have your vehicle inspected by a qualified mechanic to diagnose and address the issue. A bad coolant temperature sensor can cause a range of problems and should be addressed promptly to avoid further damage to your vehicle’s engine.

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Reasons Behind a Faulty Coolant Temp Sensor

There are several reasons why a coolant temperature sensor may fail or become faulty, including:

Age and Wear:

Over time, the coolant temperature sensor can deteriorate due to normal wear and tear, which can cause it to malfunction or fail.

Corrosion:

The coolant temperature sensor is exposed to the coolant in the engine, which can cause corrosion over time. Corrosion can damage the sensor and cause it to malfunction.

Wiring Issues:

The wiring that connects the coolant temperature sensor to the engine control module (ECM) can become damaged or corroded, which can cause inaccurate readings or a complete failure of the sensor.

Contaminated coolant:

If the coolant in your engine becomes contaminated, it can cause the coolant temperature sensor to malfunction or fail. Contaminants such as dirt, debris, or rust can damage the sensor.

Overheating:

If the engine overheats, it can cause damage to the coolant temperature sensor. Overheating can cause the sensor to fail or malfunction, leading to inaccurate temperature readings.

Electrical issues:

Faulty wiring, a blown a fuse, or a malfunctioning ECM can cause the coolant temperature sensor to fail or malfunction.

Incorrect installation:

If the coolant temperature sensor is not installed properly, it can cause it to malfunction or fail.

In order to prevent a faulty coolant temperature sensor, it’s important to have your vehicle’s cooling system regularly serviced. 

Cost to Fix A Faulty Coolant Temp Sensor

The cost to fix a faulty coolant temperature sensor can vary depending on several factors. It includes the make and model of your vehicle, the severity of the issue, and where you take your vehicle for repairs. Generally, the cost to replace a coolant temperature sensor can range from $50 to $250, including parts and labor.

When you identify the symptoms of a bad coolant temp sensor, then you can get the right estimate. If the issue is simply a wiring problem or a blown fuse, the cost may be relatively low, around $50 to $100. However, if the sensor itself is faulty and needs to be replaced, the cost may be higher. It can range from $100 to $250 or more, depending on the make and model of your vehicle.

It’s important to note that these are rough estimates, and the actual cost can vary depending on your specific situation. Additionally, if there are other issues with your vehicle’s cooling system, such as a leaking radiator or a malfunctioning water pump, these issues may need to be addressed at the same time, which can increase the overall cost.

If you suspect that your vehicle’s coolant temperature sensor is faulty, it’s important to have it inspected and repaired by a qualified mechanic as soon as possible to avoid further damage to your vehicle’s engine.

Frequently Asked Questions