What to Do if Your Car Won’t Start in the Cold

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Let’s paint the scene: you shiver your way to your car in the morning. First, you have to deal with the layer of ice that’s coating it. Next, you have to pry your way into the driver’s door and throw your key in the ignition. You turn it, and nothing happens. So much for making it to work on time.

This all-too-real start to the morning has happened a lot to us. We did some research and found different ways to fix the problem. In this guide, we’ll explain what you can do if your car won’t start in the cold. In the end, we’ll give you some tips to avoid it in the future. Hang in there, we’re here to help!

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How Does Your Car Start?

Before troubleshooting the issue at hand, it’s important to get a little detail about how your car starts. Don’t worry, we’re not going to go overboard and bog you down with details.

Whether you have to turn your key or push a button, the same process is going on under the hood:

First, your battery gives juice to a small starter engine. This starts moving and engages a larger gear.

Car-starting-system
Car starting system diagram

Now, your engine will turn over. The pistons will start moving and pumping air and fuel.

Your spark plugs fire, making sparks of electricity that ignite the fuel-air mixture. Viola, you now have a running car.

Why Does the Cold Affect Your Car Starting?

When it’s really cold, materials start to act a little differently. For instance, water will freeze, liquids will move slower, metal will get smaller (by very small margins), and chemical reactions start to get a little wonky.

Looking at the previous process we described, there is one major place where the cold affects your car starting — the battery. The scale of the pistons, spark plugs, or starter engine shrinking in the cold is too small to make a difference.

Cold-winter

Motor oil, transmission fluid, brake lines, and antifreeze will get thicker, move slower, and might be tougher to circulate through your car. However, the leading reason for problems in the cold is the increased electrical resistance in your battery and the slowed-down chemical reaction.

AAA reports that at 0 degrees Fahrenheit, your battery loses 60% of its power. That means that you need plenty of juice in your battery to get started in a cold winter morning. At 32 degrees Fahrenheit, expect to lose about 35% of your battery’s power.

Without a battery, your car can’t perform the first step of the startup process.

What to Do if Your Car Won’t Start in the Cold

Now it’s time to talk specifics: what are you supposed to do when you turn the key on a cold morning, and nothing happens? Here are a few common fixes to problems you might be having.

Cycle the Key

Your key can be turned to two different settings — one is called “start” and the other is the ignition. In the start position, the electronics will boot up like your radio, lights, and indicators, but the engine won’t start.

You can use this to your advantage to warm up the battery a little. From the off position, turn the key to start and back to off. Do this about 10 times before trying to fully turn the key and start your car.

Starting-a-car
Cycling the ignition key

If it doesn’t work, try it 2 or 3 more times after waiting a few minutes. This process is called cycling the key and it can give your battery and starter the boost they need.

If nothing turns on when your key is set to the start position, then your battery might be dead. It doesn’t hurt to check your battery.

Check Your Battery

As we keep mentioning, the battery is the prime suspect here. We have a troubleshooting guide that steps through 8 ways to tell if your battery is dead or dying. We suggest starting there and seeing if that clears up the problem.

You’re just trying to see if your battery has enough power to start your car. You can use an ammeter to read the voltage across your battery. When the car is off, you should get a reading of around 12.5V. If it’s significantly lower, you know what the problem is.

A battery replacement might be needed for your vehicle.

Make Sure Your Oil is Full

If your engine keeps trying to turn when you turn the key, it might not be the battery. An engine that’s really struggling to turn on might be telling you that your oil level is too low.

Since the oil will be moving slower since it’s cold, it could be what’s stopping your car from starting. Pop the hood and look at the oil level by checking the dipstick.

Oil-dipstick
Checking the oil level

If the oil level is low, then you might be able to get away with just topping off the oil reservoir. If it’s dangerously low, you might need to track down the source of your oil leak and fix that first.

Are Your Fluids Frozen?

There are a few different fluids in your car that can freeze in serious conditions. If any of these fluids freeze, your car can be inoperable.

In the case of fuel lines freezing, your car will either not start at all, sputter when it does start, or come to a random stop while you’re riding down the road.

If you have water in your fuel lines, it can freeze and block the lines. There’s no real DIY way to fix this problem, so you’ll have to take it to a mechanic.

Try a Jump-Start

A jumpstart is a quick way to get you back on the road so you’re not late for work. We recommend a tool that allows you to jumpstart your car on your own without a second car to hook up to.

Read our guide for safely jump-starting your car using the easiest method. If the jump works, make sure you keep a close eye on your battery in the coming weeks.

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Jump-starting the car

Check Your Starter Motor

The final piece to the puzzle is your starter motor. If you turn your key and hear a clicking sound, it could be a faulty starter motor.

Even with perfect fluid lines and a juiced-up battery, a dead starter motor will prohibit your car from starting. If your lights are turning on but your car isn’t, you can rule out the battery and start blaming the starter.

You’ll have to replace the starter assembly if you want to get back on the road. This is a pretty hefty project that might take you a day or two to complete, so make sure you’re prepared if you want to tackle it on your own. Otherwise, you can always take it to an auto shop.

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Car starter in the engine bay

Avoid This Problem in the Future

After working your way through a car that won’t start in the cold, you’ll want to know some tips to avoid it in the future. In this section, we’ll give you exactly what you’re looking for.

Park in a Garage

If you have access to a garage, we suggest you park your car in it overnight. Not only does it protect the exterior of your ride, but it also saves the internals by keeping it away from nasty outside temperatures.

A carport can also work in this situation. If you don’t have the luxury of parking in a garage, you might consider putting a cover over your car. This won’t protect against the temperatures, but at least it will give you a nice barrier against moisture that can freeze inside your car.

Car-garage

Winterize Your Car

For our friends in the northern bits of America, you should think about a yearly winterization of your car. This means taking a close look at your fluids, battery, and tires. This check ensures that you don’t have to deal with a dead car in the morning.

It’s also a good idea to get winter tires.

Does Your Battery Need to Be Replaced?

If your battery’s voltage is below 12.5V, you should consider getting a new battery. Batteries are more expensive than you might think, but they’re easy to replace if you use a specialized car battery removal tool that we recommend.

Take Time to Warm Up Your Car

If you have a remote start option on your car, you’re in luck. Simply idling your car for a few minutes in the morning will warm everything up and get the fluids flowing.

Make sure it take it easy the first minutes after starting your car in the morning. Driving steadily will help warm up your engine without overloading or straining the components.

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Coolant temperature gauge – let it warm up

Keep Your Gas Tank Full

Starting your car in the cold actually burns a lot more fuel than usual. If you were planning on hitting the gas station on your way to work, you might burn up the last bits of gas in your tank.

When you know cold weather’s coming, try to always keep at least a quarter of a tank of gas. Your future self will thank you.

Conclusion

Knowing what causes your car not to start in the cold weather is the first step. After diagnosing and fixing the problem, you’ll be back on the road in no time. We just covered a few things to check, and some additional steps to take in the future to avoid this problem. Check out our blog for more car tips and tricks, and make sure you have the right accessories and tools to keep your vehicle running smoothly.

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Ernest Martynyuk

An automotive enthusiast who's been tinkering with vehicles since I was 15-years old. Repairing automotive electronics has been my main job for over a decade now and have a passion for everything technical regarding cars.

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