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4 Signs Your Coolant Temperature Sensor is Faulty

September 17, 2024

The coolant temperature sensor is responsible for monitoring the temperature of the coolant in your car engine.

Monitoring of the engine coolant is necessary as the engine’s fuel requirements are higher when it is cold, and lower when the engine is warm.

Upon measuring the coolant temperature, the sensor passes on a signal to the car’s computer. This signal is then used to adjust both the engine timing and fuel injection. This allows for optimal engine performance.


If the computer detects that the engine is heating up too much, the performance settings will be adjusted to prevent overheating.


Faulty Coolant Temperature Sensor – 4 Common Symptoms

It’s important to know that if the coolant temperature sensor of your car is failing, it could damage your car engine. Don’t ignore the following signs–


Fuel Consumption Increases

One of the very first indications that you might have a faulty coolant temperature sensor is when you notice a drop to your fuel economy. The reason this happens is as follows:

  • The faulty sensor might send a wrong signal to the computer, leading to a miscalculation in the engine timing and fuel calculation.
  • If the computer keeps receiving a cold signal from the faulty sensor, it will interpret this as if the engine is cold and continue to inject more fuel.
  • This action will not only lead to poor fuel economy but more importantly, it can impact engine performance.

Check Engine Light Flashes

If your check engine light starts flashing, this could also indicate a faulty coolant temperature sensor. Any time this warning light comes on, our advice to car owners is to have it checked out immediately to avoid potential engine trouble.

If you are unable to figure out the trigger for the “check engine light” warning, visit a professional mechanic as soon as possible.


Engine Overheating

If the coolant temperature sensor malfunctions, it could cause your car engine to get overheated. While sometimes a faulty sensor sends a permanent cold signal to the engine, it can also send a permanent hot signal.


The computer will again miscalculate the signal and cause the engine to heat up instead of cooling it down. When this happens, the car might misfire, or it could lead to engine knocking.


Black Smoke from the Exhaust

Black smoke coming out of your car’s exhaust pipe could be another indication that your car’s coolant temperature sensor is faulty or failing. Here’s what happens:

  • Faulty readings from the coolant temperature sensor can cause the engine to miscalculate the air-fuel mix in the engine.
  • Any time the air-fuel mix ratio is not in proportion, and if the fuel mixture becomes too rich, the fuel will not be able to burn up inside the combustion chamber.
  • As a result, the fuel will burn up in the car’s exhaust pipes which causes the exhaust to release black smoke.
  • If the amount of black smoke coming from a car is excessive, it is best not to attempt to drive the car.
  • If you notice this with your car, get your car checked out by a pro ASAP.


Don’t Ignore the Warning Signs

The coolant temperature sensor is a crucial component for ensuring your engine performs at an optimal level. It is based on the signals from the sensor that the car computer calculates engine timing and fuel injection. If the signal is wrong, this important calculation will be misjudged.

If you notice any of the above signs, have your car checked immediately to avoid potential engine trouble.


Reliable Car Maintenance with Professional Auto Experts!

If you suspect a coolant temperature sensor issue, visit us at Virginia Auto Service for a fast diagnosis and resolution of the problem. If you need any other car repair service or even if you are looking for routine maintenance, we can help.


Give us a call today at 602-266-0200 or schedule a visit with us online at your convenience.

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