Skip to Content

Can Low Coolant Cause Check Engine Light? (Read This First!)

Our means of transport have remarkably evolved, beginning with the discovery of wheels and relying on horse carts and progressing to steam engines and finally the modern-day combustion engines.

It was easy to recognize a sick or weak horse, and the steam engine was also pretty straightforward, but present-day combustion engines are highly complex, requiring a handful of devices and accessories to figure out anything.

The combustion engine’s thermodynamic operating principle is heavily reliant on temperature balancing. Various factors contribute to the engine reaching a satisfactory condition, and one of the key agents of establishing equilibrium is the coolant.

So, what happens when you drive a car with a low coolant level? Let’s find out.

Can low coolant cause check engine light?

Low coolant will almost probably result in a slew of problems, including the appearance of the check engine light. The primary function of the coolant is to keep the engine at a safe operating temperature. A low coolant level will throw off the engine’s balance and efficiency.

The car engine is well equipped with mechanisms that help it maintain a suitable temperature to provide optimal performance.

There are sensors and a thermostat that keeps an eye on the internal temperature, if there are any irregularities in the atmosphere they will send a distress signal to the power control module. Understanding a low coolant level in the engine is a little bit tricky.

For starters, if the coolant is low, there would be a sudden drop in temperature, the thermostat, and temperature sensor may record it and treat it as an irregularity or resting phase, but the engine is running on low coolant and the internal temperature will be going up.

At a point in time, the inner temperature would be so high that may cause damage to the sensors, the data transfer between the power control module and sensor may be cut off and the check engine light will appear.

3 reasons why low coolant causes check engine light to come on

There can be multiple reasons why low coolant causes check engine light on. Let’s find them out.

Rise or fall of temperature:

Temperature plays a vital role in the thermodynamics aspects of the engine, and coolant helps to maintain the balance.

If there is a rise or alarming drop in temperature and not enough coolant to sustain equilibrium then the engine light is sure to give a warning signal. So a drastic rise or dip in temperature will cause the check engine light to come on.


the miscommunication between the engine temperature sensor and power control module can also be the reason behind the check engine light coming up.

There are several temperature sensors present in the engine which will detect the temperature conditions, and send data to the power control module.

The lack of coolant can damage or neutralize some of the sensors and the power control module will activate the check engine light.

No dedicated light:

Most vehicles don’t have any dedicated light or gauge that will warn you about low coolant levels. In most cases, the check engine light will be activated to notify you about the internal situation.   

What happens when the coolant gets low in the car? What light comes on when coolant is low? 

The coolant is necessary to maintain the equilibrium conditions for the engine to perform. The temperature inside of the engine can get drastically low and then rise to the pique if the coolant level is too low.

The fluctuation of temperature is an enormous red flag and most of the time the check engine light may appear.

The thermodynamics principle works on equilibrium conditions, if the temperature drops too low while running then the car might start shaking and this small irregularity may not be noticeable for someone.

Running on low coolant may not look like a big deal, all the data from the thermostat and temperature sensors may not pique your interest but things could go bad in seconds.

When the coolant is absent or low then there isn’t anything else that will help the inner temperature to be at equilibrium. It may be too late when the sensor sends the distress signal.

In most cases when the engine light appears the problem is found to be a low coolant level. It would be better to find a vehicle with a separate indicator for coolant level and a more specific warning system, it will help you keep an eye on the little things.

What are the signs of low coolant?

You can see many signs of low coolant in your car. Let’s get to know them.

Unusual fluctuation in temperature:

the first sign of low coolant would be the temperature gauge and sensors showing fluctuating data.

There are temperature sensors provided in specific locations in the engine & related mechanisms and any sort of abnormal temperature rise or fall will definitely alert and sometimes damage those sensors.

Lack of coolant will definitely cause a chaotic atmosphere in the engine and can certainly lead to permanent damage.

Warning light turned on:

Due to the low coolant level, the chaotic situation created inside the engine will surely cause major or minor damage to the temperature sensor.

When the power control module receives a distress signal or won’t receive any data from the sensors, it will activate the warning light.

It’s not a sure method but in most cases, if there isn’t any dedicated light for coolant then the check engine light gets activated.

Trembling ride:

low coolant level can also make your vehicle shake and create crackling noise. If you are experiencing a trembling ride then it’s high time you took care of that issue.

Engine shut down:

the thermodynamic principles of car engines greatly depend on the cooling system. The low coolant level will abrupt the equilibrium and may cause the engine to shut down.

Before shut down there is a high probability that you will see fluctuations in the temperature gauge and all the warning lights being activated. Engine shut down can be the worst thing you have to face because of the low coolant level.

How to fix low coolant in your car?

To fix the low coolant issues, you can follow a checklist. Check below to find them out.

Keeping it fully loaded:

There is no other alternative to do a regular check-up on all the necessary fluid levels that help your vehicle engine to work efficiently. Brake oil, engine oil, other lubricant are necessary, same goes for the coolant.

Low coolant levels can create some unwanted situations and may cause damage to your engine. Regular maintenance and keeping the coolant fully loaded can be the most effective way to keep your engine safe.

Being patient:

Let’s assume a scenario where the check engine light pops out & you stop your car and fill in coolant but the warning light is still on, in such situations the only thing you can do is wait patiently.

It needs time for the coolant to do its magic, also it takes even more time for the engine sensors to recover.

However, if the check engine light or for some cars the dedicated coolant light is not turning off then there might be major damage in the sensors.

Keeping an eye on the regulator:

this is a little bit tricky, you can add coolant, keep it at a suitable level, and never have any inconvenience or any warning light incident but your engine may still be damaged due to low coolant level.

The regulators are essential for keeping the engine from overheating. However, when the regulator’s maintenance is ignored, minor leaks and blockage start to decrease its efficiency, and it might be too late to rely on a power wash to clean and repair it.

A faulty regulator won’t let the coolant work properly. Keeping an eye on the performance may give you a few hints and may save you from costly repairs.  

Will low coolant throw a code?

Yes, a low coolant will absolutely throw a code. Vehicles have several sensors that send data to the power control module and other receivers.

If the internal temperature, lubrication, and all the necessary aspects are up to the mark then both sending and receiving ends will stay neutral.

However, if there is a surge or dip in temperature at an alarming rate then the sensors will send distress signals, all the warning lights will pop up. If you get your hands on a scanner, it may show the P0128 code which is an indicator for low coolant level. 

Final Thoughts 

The coolant’s main purpose is to maintain a suitable temperature for the engine to function properly. Having a low coolant level will abrupt the balance and efficiency of the engine, it will certainly cause several malfunctions and perhaps turning on the check engine light.