Can coolant leak cause check engine light

Can Coolant Leak Cause Check Engine Light

Have you ever wondered why that mysterious “Check Engine” light suddenly appears on your car’s dashboard? Do you suspect the coolant leak in your car? So, can coolant leak cause check engine light?

Yes, a coolant leak can cause the check engine light. But indirectly. Engine overheating, thickened coolant in cold temperatures, a faulty coolant level sensor, and the lack of a dedicated coolant light or gauge can all contribute to the check engine light illuminating.

I was also in your situation, where I experienced the check engine light with a coolant leak. So, I did thorough research to find out how coolant leaks cause the check engine light and how to prevent it.

What Is an Engine Cooling System?

The engine cooling system is a crucial component of a vehicle that is designed to regulate and maintain the optimal operating temperature of the engine. When the fuel-air mixture is combusted in the engine, a significant amount of heat is generated. So, the heat should be reduced to prevent overheating and engine failure.

What Is the Need of Coolant in The Cooling System?

The coolant liquid plays a vital role in the engine cooling system for several reasons. Here are the tasks of coolant in the cooling system:

Tasks of coolantExplanation
Heat DissipationCoolant absorbs and carries away heat generated by the engine through combustion.
Temperature RegulationHelps maintain the engine within its optimal operating temperature range for efficient performance and reduced wear.
Prevention of Boiling and FreezingCoolant has specific properties to prevent boiling at high temperatures and freezing at low temperatures.
Corrosion ProtectionContains additives to protect engine components from rust and corrosion, ensuring the longevity of the cooling system.
LubricationSome coolants possess lubricating properties, reducing friction and wear within the cooling system.
Anti-CavitationCoolant additives minimize the risk of cavitation, which can damage engine components.

Can Coolant Leak Cause Check Engine Light?

Yes, it happens due to problems caused by low coolant levels. A coolant leak leads to low coolant in the radiator. Here are the situations where low coolant due to a coolant leak causes the check engine light to come on.

Engine Overheats

Heat meter of a car, engine overheats

Engine overheating refers to a situation where the temperature of the engine exceeds its normal operating range. When there is a coolant leak, the coolant in the cooling system is not enough to effectively control the engine’s temperature. This triggers the check engine light.

Lack of a Dedicated Coolant Light or Gauge

Oil pressure or battery charge systems have separate warning lights. But coolant levels do not have a dedicated warning light or gauge. Consequently, if the coolant level becomes too low due to leakage, the engine may overheat. Then the check engine light to come on.

Thickened Coolant

When there is a coolant leak, the coolant level in the radiator becomes low. So, the coolant in the radiator and engine becomes thicker and less fluid. this happens especially in cold temperatures.

Faulty Coolant Level Sensor

Miscommunication between the coolant level sensor and the car’s computer can occur if the sensor is faulty. So, the check engine light comes on due to incorrect signals.

Coolant level sensor

What are the Signs of Coolant leak?

You can visibly see low coolant level in the radiator. Car engine overheats due to low coolant levels and the engine will shut down abruptly due to overheating. Maintaining a proper coolant level is vital for keeping the engine to prevent overheating issues. You should check coolant levels regularly. If it is low, add some.

How Did I Check and Add Coolant to My Car?

Here is how I check and add coolant to my car: I will mention it as a step-by-step guide, so you can easily follow my steps.

Important: Make sure to check the coolant when the engine is cool. This avoids any burns or damage.

Step 1: Locate the Coolant Reservoir

First, I opened the hood. I found the coolant reservoir, which had a picture of a radiator on the cap.

Step 2: Check the Coolant Level

I looked for the cold fill line on the reservoir. I was lower than the recommended level. So, I made sure the remaining coolant wasn’t contaminated or dirty.

Step 3: Open the Cap

I carefully opened the cap, and I removed the cap from the reservoir.

Step 4: Add Coolant

I poured the coolant into the radiator or reservoir until it reached the cold fill line. I was careful not to overfill.

Note: You should select the appropriate coolant type for your vehicle. I put universal coolant. There are different coolant types.

E.g.: – Regular coolant, Extended-life coolant, Universal coolant.

Step 5: Secure the Cap

Then, I closed the cap tightly. I double-checked that the cap was seated properly. It should fit snugly to prevent coolant leaks.

Important: If you drive your car with a loose radiator cap, it will cause the gasket to melt due to the high temperature.

If the check engine light is still illuminated after adding coolant, it’s important to be patient and allow the sensors sufficient recovery time. Or you can just clear the check engine light manually.

Note: Regularly check and maintain the fluid levels in your vehicle. If you notice the coolant level consistently dropping, it may indicate a coolant leak that requires professional attention.


Can you drive a car with a coolant leak?

Although there is no immediate danger to your health from driving with a coolant leak, I strongly advise against it. Driving a car with coolant leaks may seriously harm your engine. Your engine might overheat and cost you a lot.

Can I use water instead of coolant?

Technically, you may put just water in your cooling system, but it isn’t advised as a long-term fix or in severe weather conditions.

How often should coolant be changed?

A coolant flush is generally recommended every 30,000 miles or three to five years, whichever comes first. Depending on the manufacturer, your car’s owner’s manual should also specify a more precise interval. The type of coolant and driving climate are other considerations.

Why does coolant need to be changed?

When coolant become old, it becomes acidic. Along with the car’s heating system, the cooling system’s radiator, water pump, thermostat, radiator cap, hoses, and other parts are all prone to corrosion. And that might result in an overheated car engine.


Can coolant leak cause check engine light? Yes, low coolant levels caused by coolant leaks can indeed cause the check engine light to illuminate in a vehicle. If the check engine light persists or other symptoms persist, it is advisable to seek assistance from a qualified mechanic. They will diagnose and repair any underlying issues causing the coolant leak or engine overheating.

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