Car Repair and Maintenance

Can a Bad Coolant Temperature Sensor Cause Car Not to Start?

Can a bad coolant temperature sensor cause car not to start? One of the most crucial sensors in a car is the coolant temperature sensor. It is a thermal resistor that is used to gauge the coolant temperature of the engine. The car’s ECU uses this measurement to modify how much gasoline is injected into the combustion chamber.

A bad coolant temperature sensor can cause a car not to start by preventing the engine control module from determining the correct air/fuel ratio for the engine. This can lead to poor performance or a complete failure to start. It’s recommended to check the coolant temperature sensor if your car is having starting issues.

The sensor’s job is to communicate the engine temperature to the computer so that it can make the required changes.

The computer won’t be able to accurately regulate the fuel and air mixture if the sensor isn’t operating properly. This might cause a lot of issues. It’s crucial to take your car to a technician to have it examined if you detect any problems. Your engine might sustain more problems if the issue is ignored.

Can a bad coolant temperature sensor cause car not to start

What does the coolant temperature sensor do?

To figure out if a bad coolant temperature sensor cause a car not to start, let’s have a look at its working principle.

The Engine Coolant Temperature Sensor in your car is crucial in ensuring that your engine operates within the ideal temperature range and that it doesn’t operate over the alert level without telling the driver on the instrument panel of a possible problem. 

Preventive maintenance and regular tune-ups can help identify these possible problems before they become expensive repairs. While you may not be aware of when your car could be about to overheat, the vehicle coolant temperature sensor probably is. The sensor monitors the temperature at which the engine is running and notifies the on-board computer when a possible issue arises.

The coolant temperature sensor measures the temperature that the thermostat and/or the coolant itself are emitting. As a result, the on-board control system receives the temperature after that. The car computer will then use this temperature data to decide whether to keep running the engine or change some of its operations in an effort to maintain a desirable engine temperature.

The cooling fan could be triggered to turn on or off as soon as the control system gets the temperature from the CTS. Additionally, it can indicate that a richer fuel mixture is required or that the exhaust gas recirculation should be opened.

Can a bad coolant temperature sensor cause a car not to start Completely?

For a car not to start completely, it can’t solely be the fault of the bad coolant temperature sensor. The coolant temperature sensor will not cause the car not to start, even though one of its bad signs is the engine stalling quickly after starting, particularly when the engine is cold.

Let us explain why “the no start issue” is not caused by a bad coolant temperature sensor. The car’s “no start” status is not due to a malfunctioning or dead engine coolant sensor. By examining the ECT sensor’s operation, the cause of this is evident.

The purpose of the engine coolant sensor in a car is to measure and transmit the engine coolant’s temperature to the ECU, or electronic control unit, of the vehicle.

As the coolant absorbs the heat from the engine, it measures the temperature change to calculate the engine temperature. Using this measurement, it then adjusts the engine temperature by injecting the right quantity of fuel.

Since it is a thermistor, the engine coolant temperature sensor processes the data from the ECU at a resistance that is related to the temperature of the engine coolant and delivers it back to the ECU.

Therefore, even if the ECT sensor is dead, it won’t prevent your car from starting; rather, it might result in a difficult start and other major issues.

Where is the coolant temperature located?

Typically, the sensor is found in the intake manifold, close to the thermostat. Manufacturers sometimes place this sensor closer to the cylinder head in most modern vehicles (see Holstein Parts).

These sensors are installed on each row of combustion chambers in V-shaped engines in pairs. Additionally, the fan and ECU can each have a pair of sensors installed separately.

How to check the coolant temperature sensor

Simply taking the coolant temperature sensor out of the slot is the quickest and simplest method to check it. The engine will immediately enter emergency mode, the cooling fan will activate, and the fuel mixture will be created depending on the readings of other sensors, as you can see right away. The sensor must be changed if the engine starts to run better at the same time.

Diagnostic tools like an OBD are needed for the coolant temperature sensor’s subsequent test. The temperature measurements on a cold engine, such as in the morning, must be checked first. The reading must match the surrounding temperature.

A very little inaccuracy of 3–4 degrees is permitted. Additionally, the temperature should increase gradually after starting the engine without fluctuating between measurements.

A sensor issue would be evident if the temperature suddenly rose from 30 degrees Celsius (86 degrees Fahrenheit) to 32 or 33 degrees Celsius (90- or 92 degrees Fahrenheit).

How to Fix a Bad Coolant Temperature Sensor

If you have discovered that your bad coolant temperature sensor might be the cause of your car not starting, then you need to fix it without visiting an auto mechanic.

The first step is to physically inspect the sensor. It might be broken or damaged, so this might not set off an error code. You will need to physically inspect it to make sure that it is in a good condition physically.

Required Tools to fix a Bad Coolant Sensor

To get started with this project, you will need some tools. Fortunately, to remove, inspect and replace a bad coolant sensor causing a car not to start, you won’t need much tool.

  • Wrench set

Required Materials

Here’s a list of parts you’d have to buy.

  • New engine coolant temperature sensor


As mentioned earlier, the answer to the question “can a bad coolant temperature sensor cause car not to start” is No.

Although your car will start despite having a bad coolant temperature sensor, it is never advisable to have a damaged coolant temperature for a long time. The reason is that it can cause more damage to other car components.

If you have a bad coolant temperature sensor, you should get the help of a professional technician immediately to avoid major damage.


Latest posts by Bernard Juchli (see all)

Bernard Juchli

Bernard Juchli is an experienced racer, mechanic and team owner who trusts Avon Tyres.Bernard is the lead driver and force behind his Big Dog Garage Race Team. He is the General Manager and Chief Mechanic of Jay Leno’s Garage. Bernard and his crew of seven are responsible for all repairs, restoration and fabrication of Jay’s incredible automobile and motorcycle collection.

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