Can A Bad Coolant Temp Sensor Cause Rough Idle?

Rough idling in vehicles is a very unpleasant condition for both the drivers & the passengers. The coolant temp is also suspected in search of the reasons behind the rough idle. Let’s start with the short answer.

Yes, a bad coolant temperature sensor can cause a rough idle. When the coolant temperature sensor of the vehicle gets damaged or fails to work, it transmits false signals to the ECU. As a result, you experience rough idling.  

More information is still required, right? Here in this article, we will cover every bit of detail about whether coolant temperature sensors cause rough idle. So, stay tuned! 

How Is The Bad Coolant Temp Sensor Contributing To The Rough Idle?

As you already know, a bad coolant temp sensor is a potential cause of the rough idle as it sends false signals to the Electric Control Unit or the ECU. 

Due to the ECT’s transmission of false temperature signals to the ECU, the electric control unit starts to adjust the fuel combustion according to the false signals. 

As a result, your vehicle has a fuel injection delivery fluctuation. The ECU makes the fuel injection mixture either too rich or too lean, leading to rough idling in your vehicle. 

You must know that most vehicles have two different coolant temp sensors. One is reporting to the dash gauge, and the other one to the ECM. 

If you have a bad dash gauge sensor, the electric control module remains unaware of the failure. 

When that is the case, the performance of your engine will not be affected due to a busted sender of the dash gauge. 

The problem may be happening otherwise. This means the rough idling may be due to the faulty engine coolant temp sensor.

How Serious Is The Bad Coolant Temp Sensor Problem? 

Bad Coolant Temp Sensor Problem

When the coolant temp sensor of your vehicle goes bad, it can lead to serious engine damage if you leave it unencountered.

Actually, what happens, when there is a bad coolant temp sensor, it causes the cooling fan to run intermittently or not to run as well. It causes the overuse or overheating of the cooling fan motor. 

When that happens, the overheating can lead to possible serious engine damage, which we have already mentioned. 

Besides, in a vehicle, the engine’s air-fuel ratio keeps it running smoothly. When this air-fuel ratio gets crooked, your engine will experience poor fuel economy. As a consequence, the engine will not run smoothly or will not run well. 

Also, the coolant temp sensor plays an important role as it gives the information to the Electric Control Module or ECM that it needs to optimize the circulation to run the engine. 

When the coolant temp sensor fails to do so due to its fault, the problem of the engine is obvious.

How Much Will It Cost To Replace the Bad Coolant Temp Sensor? 

Replacing the bad coolant temp sensor can cost, on average, $150-$200, estimated for the parts $23.29 – $28.47 & for the labor, it is $109.74 – $134.13. 

You may also notice a change in the average cost based on the mechanics you choose for the task, where you live, or the model of the car you are driving.

Here, the chart below represents the estimated average price for different car models for you to get a rough idea. 

Car ModelsPart CostLabor CostTotal Estimated Average Price
2016 Mazda 6$20.16$94.99$115
2012 Chevrolet Impala $20.69$94.99$116
2011 BMW X3$28.95$94.99$124
2008 Porsche Boxster $26.53$180.48$207
2007 Saturn Aura $27.61$123.48$151
2009 Mercedes Benz R320$11.44$132.98$144

Hoe to Prevent Bad Coolant Temp Sensors Causing Rough Idle?

The electric coolant temp sensor is a very important component of the automobile vehicle which operates by two things- the temp of the engine coolant & the temp of the atmosphere. 

To keep your car away from rough idle caused by the electric coolant temp sensor, you can try to clean it. 

Besides, the price of the sensor is hugely cheap, about $15-$30. Therefore, whenever the coolant temp sensor dies or shows any malfunction, replace it. Besides, the replacement process is pretty straightforward. 

That’s why it is better to resolve the issue without being any more worried & not to bear the issues caused by it.

Frequently Asked Questions [FAQs] 

Now here in this subsection, we are going to cover some of the queries that are frequently searched in different forums by customers & automotive enthusiasts. 

Read to know some concerns about the bad coolant temp sensors & the problems created through them. 

Can A Bad Coolant Temp Sensor Cause An Engine To Misfire?

A bad coolant temp sensor causes the engine to misfire. When the coolant temp sensor is defective, it fails to transmit the hot signals causing the computer to counterbalance them. As a result, there is a misfire in the engine. 

Can A Faulty Coolant Temperature Sensor Cause A Car Not To Start?

When the temp reading becomes too high than the ambient temp, the computer may notice it as a problem & as a result, there is a check engine light on. A bad coolant temp sensor can’t cause a car not to start. 

Does The Coolant Temp Sensor Affect The Ac? 

In short, the coolant temp sensor affects the ac on your automobile vehicle. When the sensor fails & transmits an inconsistent cooling signal, it hampers the function of the ac. The ac can’t maintain a comfortable temperature in the cabin. 

Can A Coolant Temperature Sensor Cause A Car To Stall? 

When you are experiencing stalling of a car, there is a possibility that the coolant temp sensor is faulty. Because of a defective coolant temp sensor, it tells the computer for the car to overheat when it is not. The computer may then reduce fuel, causing the car to stall. 

What Happens If You Unplug The Coolant Temperature Sensor? 

If you unplug the coolant temp sensor from your vehicle, the temperature gauge will stop working. Besides, it can turn off the engine through the ECM. The driving may become hard or unpleasant without a bad coolant temp sensor.

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