Updated at: 22-07-2022 - By: Lucas

Various sensors now dictate how modern autos behave. The electronic control unit receives information from these devices based on their analysis of certain parameters (ECU).

One of the bad signs of a faulty coolant temperature sensor is that it might cause an engine to stall shortly after starting, however this only happens when the engine is cold. However, if your automobile still won’t start, you might want to start by looking for other problems.

The coolant temperature sensor should be changed if it shows evidence of dysfunction. When you start the automobile and discover these and other defects because of incorrect information, you know something is wrong.

A properly functioning coolant temperature sensor requires a normal level of coolant in the system. It’s important to keep the system lubricated at all times.

What does the coolant temperature sensor do?

Can A Bad Coolant Temperature Sensor Cause Car Not To Start

When the engine is running, the cylinder block generates heat, which dissipates through the combustion chamber. The radiator and the unit’s cooling system both use coolant to remove heat from the system. You need to know how the coolant temperature sensor works in order to determine what it impacts. In fact, it’s job is to transmit engine temperature signals to the ECU.

This sensor’s performance can be influenced to improve vehicle controllability while driving with an unheated engine, to maintain a constant idle speed, and to prevent harmful emissions. Sensor failure or corrupted data transmission to the control unit might cause significant issues.

The next procedure will go off without a hitch thanks to the coolant temperature sensor.

  • Fuel enrichment process. If the ECU receives information about the low temperature of the coolant, then the injection time for the injectors is recalculated. This action contributes to the stability of idling. Gradually, the temperature rises, and, based on these readings, the injectors deplete the mixture. If the sensor does not give correct information, then a rich mixture will occur
  • Increase in rpm during start. The engine may stall if the engine speed is insufficient when starting. A command from the ECU to accelerate the engine speed helps to get rid of this so that the car does not stall.
  • Exhaust recirculation. To maintain controllability during startup, the recirculation valve must be closed before the system reaches operating temperature. If this does not happen, then the car will get unstable rpm or a stalled car.
  • The torque converter clutch in the gearbox is not blocked until the engine warms up. This is done to maintain optimal handling.
  • Turn on the cooling fan. Based on data from the coolant temperature sensor, the radiator fan starts or turns off. It helps to reduce the temperature of the refrigerant faster. In some car models, a separate sensor with a single function is used exclusively to start this fan.

Where is the coolant temperature located?

As a rule, the sensor is situated in the intake manifold near the thermostat. Manufacturers less typically install this sensor nearer the cylinder head. Each row of combustion chambers of a V-shaped engine has a pair of these sensors attached to it.

The fan and ECU each have their own set of sensors.

Symptoms of bad coolant temperature sensor

Can A Bad Coolant Temperature Sensor Cause Car Not To Start-3

These symptoms may indicate a problem with the coolant sensor, which is not directly responsible for a car that won’t start.

Rough cold start

Immediately after starting, the engine shuts down. Problem solved after a few minutes of warming up. This occurs as a result of the ECU receiving inaccurate data from the coolant temperature sensor. In the case of an engine that’s already warmed up to the proper temperature, for example.

You’ll need more fuel to get a cold engine going than a hot one. Because it believes the engine is hot, the ECU provides insufficient fuel to the engine.

Bad hot start

Everything is the complete opposite in this location. The ECU’s coolant temperature sensor may report that the engine is too cold because of faulty readings from the sensor. There’s no need to worry about the engine running out of fuel. The P0172 error code may also show up in this case.

Increased fuel consumption

This is a logical outgrowth of the aforementioned condition. Consumption will rise if the engine is inundated with fuel.

The cooling fan turns on or off for no reason

When the coolant temperature sensor is reading incorrectly, the radiator fan will turn on when it isn’t needed, for example, when the engine is running at the correct temperatures but the sensor is reporting a higher temperature, causing the cooling fan to turn on rationally.

Things get worse if the sensor overestimates the readings, which can happen. The coolant may have already reached boiling point, but the sensor will interpret this as normal, therefore the ECU will not turn on the cooling fan to prevent it from overheating further.

Check engine light on

Because of the sensor’s inaccurate readings, the check engine light and/or coolant temperature error light will frequently illuminate on the dashboard of your car.

How to check the coolant temperature sensor?

Removing the sensor from the slot provides the quickest and easiest access to the coolant temperature. After pressing the emergency button, the cooling fan will come on and the fuel mixture will be adjusted according to the other sensors’ data. Unless the engine’s performance improved as well, it’s safe to assume the sensor has to be replaced.

Diagnostic equipment such as an OBD is needed to perform the following coolant temperature sensor test. To begin, use a cold engine in the morning to examine the temperature readings. The temperature should be reflected in the reading.

3 to 4 degrees of misalignment is permitted. After the engine is started, the temperature should climb steadily and not bounce between measurements. In this case, if the temperature was 30°C or 86°F, and then suddenly rose to 32°C or 92°F (90°F or 90°F), the sensor has failed.