Headed to Test a Coolant Temperature Sensor? Here’s How to!

If you are new to cars, the term coolant temperature sensor may be very new to you. This sensor is the mechanism that is responsible for telling the car’s computer the precise running temperature of the engine. This dictates the dynamics of how the engine will work. Prior to such sensors, choke was the mechanism that did it. Now, with these temperature sensors, the process is more automated, and the engine runs smoothly without freezing off in the winter and overheating in the summer.

But, why would you need to text it? Simply because it can malfunction sometimes. If the coolant temperature sensor malfunctions or dies, you could face problems like stalling, increased fuel emission, disrupted ignition timing, rough transmission, etc.

Testing the sensor isn’t difficult. This blogs instructs you on how to. Here is another of our maintenance tips that help you maintain your car better.

Steps to Test a Coolant Temperature Sensor

There are 4 simple and easy steps that you need to follow.


Step 1: Locating the Coolant Temperature Sensor

It is situated under the hood on the engine block. Just open the latch of the hood and hold it open. Use a drop light if you need better vision into the engine block. Peep in the middle of the pulleys at the front of the block. A small terminal coming out of the block itself will become visible. You will see a wire lead coming out of the terminal. Exactly this terminal and wire lead is your car’s coolant temperature sensor.

Resolving coolant temperature sensor problems
Fixing the coolant temperature sensor (photo source: Mitch Varn @ Youtube)

Step 2: Connecting with Volt-Ohm Meter

Simply take a digital volt-ohm meter. If you don’t have one, odds are that one of your neighbors might. Testing it with this meter is the surest way to tell if the sensor is fine or faulty.

Remember, connecting the right way is important. In fact, if you have a good understanding of the terminals, you can even jumpstart a car with a dead battery.

Here is how you must connect the meter to the sensor. Take the black lead of the meter and touch it to any solid metal. Now, take the red lead and connect it to the terminal end of the coolant temperature sensor. Set the reading on the digital meter to 20k range.

Step 3: Checking the Reading

You will now need to turn on the engine and let it run for at least two minutes to allow it to gain the running temperature. You will have to read the meter all this time while the engine is running.

Pay attention to what you should be seeing on the digital meter. As the engine runs, you must see variations more than 200 ohms (variations between cold and warm engine). If you see that the difference is not more than 200, you are dealing with a faulty coolant temperature sensor.

Step 4: Checking a New Sensor

If you are checking a brand new sensor, you need to follow this.

Attach the black lead of the volt-ohm meter to the body of the cold sensor (this is before turning the engine on). The reading should be 2000 ohm approx. then check the sensor in the warm sensor (after the engine is run). If the reading is not way lower than 2000ohm, you have a broke coolant temperature sensor.

In case you find it to be faulty, you must replace it at the soonest. If not, it can cause quite a few problems some of which we mentioned right at the start of this blog.