Why Does the Check Engine Light Turn On in Cold Weather?

While gearing up or preparing to stay warm during the cold months, also be prepared to do certain things to keep vehicle performance intact. During winter, various vehicle fluids and component performance are intercepted. Invariably affecting overall vehicle performance and leading to the illumination of the check engine lights.

So it’s important to know exactly why the Check engine lights in cold weather and how to fix it.  This way, you can have a smooth and optimal vehicle performance even when the weather is cold.

Check engine light in cold Weather

Why your check engine light turns on during the cold weather

In extremely cold conditions, various fluids, sensors, and other components in your car tend to function inappropriately. Invariably, this triggers the check engine light to turn. Let’s take a close look at why your check engine light turns on during the cold weather.

Low oil level/low pressure

When the weather gets too cold, the oil in your car thickens up. This not only reduces the oil level but also results in inadequate circulation of oil throughout the vehicle. The inability to circulate properly often leads to low oil pressure, causing the check engine light as well as the oil pressure warning light to turn on.

Contaminated oil

Because the oil gets thicker during the cold months, it’s easier to draw road salt, dust, and dirt as you drive. This accumulation causes your oil to break down faster, invariably triggering the check engine light to turn on. So if your Chevy or Subaru check engine light turns on in cold weather, the oil might be a culprit.

Fuel delivery system issues

During the cold months, the pumps not only work harder, but the fuel and fuel lines can freeze up due to moisture in them. This hampers the flow of fuel, preventing fuel from getting to the engine in time. Invariably leading to performance issues and eventually causing the CEL to come on.

Sensors issues

In extremely cold conditions, sensors that regulate certain parameters, such as the coolant temperature, oil pressure, emission levels, oxygen levels, vehicle speed, etc, cannot provide accurate readings to the ECU.

Because these sensors provide readings contrary to the usual range, the ECU will trigger the check engine light to turn on. The explanation should answer those asking, can cold weather affect car sensors?

Ignition system issues

Ignition system components such as spark plugs and coils can be affected by cold weather. Because engine oil becomes very viscous in cold months, it’s usually harder to crank your engine and for spark plugs to ignite the air-fuel mixture.

Again, when spark plugs get too cold, they are unable to heat up to the required temperature. This results in the inability to burn off carbon residues, leading to faster fouling of the plugs. These invariably affect combustion and overall vehicle performance, leading to the illumination of the CEL.

Battery failure

In extremely cold temperatures, your car battery tends to work harder, invariably draining and weakening faster. This is together with a reduced battery charge rate since the alternator will take longer to charge the battery. If the battery voltage drops below the required limit, it will trigger the check engine light to come on.

How to prevent check engine light cold weather

One of the best ways to deal with CEL is always keeping your car clean and avoiding leaving your car parked in the cold. The less it is exposed to cold, the less you have CEL issues. Let’s take a close look.

Use winter or lower viscous oil.

Opting for oil with lower viscosity can prevent all your oil problems during the cold months. Lower viscous oil not only prevents regular fluid shortage but also flows easily, facilitating better lubrication and quicker start-up. Just get one of these winter-grade oils particularly designed for the cold weather. More importantly, regularly check your oil conditions and never skip an oil change.

Opt for moisture control additives.

Generally, fuel can not freeze since its freezing point is far below any temperature on Earth. However, fuel contains ethanol, a highly hygroscopic additive that can absorb water from the atmosphere. It’s this water in the fuel tank or fuel lines that, in turn, freezes and messes everything up.

To avoid this, use fuel additives with moisture control or buy gasoline already mixed with antifreeze to prevent water vapor from freezing. Experts also suggest you keep your fuel tank half full to prevent icy fuel lines and regularly top off so you don’t run out of fuel.

Keep sensors clean

During winter, most sensors tend to function inaccurately because ice or snow has covered them. These sensors are located in different places, such as the wiper path, fenders, rear body panels, bumpers, grille, under the side mirrors, etc. To therefore avoid sensor issues, keep these parts clean.

For example, to keep the sensors in the wiper’s path clean, all you need to do is clear your windshield from snow, ice, or dirt. Alternatively, you can keep the sensors clean by regularly washing your car. 

Keep your spark plugs in good condition.

Your spark plugs will give in to the cold weather, especially when it is already old. To avoid all the spark plug issues in extreme conditions, try changing your spark plugs before the cold months start.

Battery maintenance is important.

The most proficient way to avoid battery issues in cold temperatures is to park your car in an enclosed storage facility. Driving longer or long distances also gives your battery enough time to recharge. Turning off unnecessary appliances helps reduce the load on the battery, invariably retaining its charge longer.

Also, test your battery condition to ensure it can handle the cold weather. More importantly, ensure you keep up with regular battery maintenance, such as watering and rust removal. Removing corrosion from battery terminals prevents electrical resistance between connections, invariably preventing batteries from working harder, especially in winter.

How to diagnose check engine light during cold weather

In many cases, when the CEL light turns on, all you may need to do is either add more fluid or fix certain malfunctioning components. However, you should first know the exact thing triggering the light to come. Here is how to fix a check engine light in cold weather.

Scan for error codes.

Start by scanning for fault codes. To do this, connect your OBD II scanner or any diagnostic tool to your vehicle’s OBD II port to see fault codes stored. These codes will help to detect the problem.

Clear fault codes

When you finish scanning, clear the fault codes and see if the check engine light appears. If it doesn’t, the weather is possibly the cause.

Warm your car

Since cold weather can trigger the CEL light to come on, let your car warm and see if the light disappears. If the light disappears, the weather is possibly the cause. Sometimes, the check engine light can even disappear on its own. But to be on the safe side, run a diagnosis.

Reach out to an expert (your last resort)

If the lights keep reappearing after doing all the above, you may need to take your car to a professional for proper diagnosis. Aside from the cold weather, there are many other factors that can trigger the check engine light to turn on.

Even in cases where you have the check engine light on but car runs fine, still have your car checked. The illumination of the CEL is an indication that something is not working as it should–minor or major. And only a proper diagnosis can point you to the issue.

Thankfully, the same process can fix any check engine light issues. So whether your Kia or Mazda CX-5 check engine light in cold weather comes on, you know exactly what to do.

Final words

The Check engine light in cold weather can come on for several reasons, including low oil level, frozen fuel and fuel lines, faulty sensors, battery, etc. To fix the issue, scan and clear any fault codes. You can, however, avoid these cold weather car issues by parking in an enclosed place and using less viscous oil.

Using fuel additives with moisture control and ensuring all sensors are clean is also another way of preventing check engine light in cold weather. However, if all these are in place yet the CEL keeps appearing, there may be other issues. Take your car to an expert for proper diagnosis and fixes.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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