What Should You Do When Your Car Won’t Start in Cold Weather?

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car won't start cold

Cold dark mornings and cars not starting. We all have experienced this at some level, especially if you live in Canada.

It’s that time of year again when the temperature starts to drop, and your car won’t start. If you’re like most people, you probably don’t know what to do when this happens. Here are a few tips to help get your car started in cold weather.

In this article, we will discuss all such scenarios and try to find out suitable solutions to those problems.

How Does the Car Start?

Before we commence with starting problems of cars in winter, let us find out how a car actually starts.

There are two basic types of internal combustion engines. And both these types of engines have a slightly different way of starting.

Spark Ignition (Gasoline Engine)

Spark ignition engines are more common than diesel engines. They use an ignition or starter coil and spark plugs for starting.

The process of starting is as such that when you press the ignition key. The car’s accessories are turned on by using current from the battery.

Then when you further press the ignition key to crank the engine, the stater coil sends current to the spark plugs. Meanwhile, the starter motor gives the first push to the pistons in cylinder heads.

Simultaneously, the air-fuel mixture is injected into the cylinder head via fuel injectors. The moving pistons compress this air-fuel mixture up to the top of the cylinder.

When the air-fuel mixture is at the smallest volume during the cycle, the spark plugs produce a spark to ignite the mixture.

This causes the piston heads to move in the opposite direction with a sudden push and the engine is started as a result.

Compression-Ignition (Diesel Engine)

The process of starting in the compression ignition engine is quite similar to the spark-ignition engine.

But they have a very high compression ratio. The compression ratio is the ratio between the volume of the air-fuel mixture at the end and the start of the cycle.

The next difference is the absence of spark plugs in the compression ignition engines. They have the same fuel delivery mechanism, the same way initial push is given to the pistons.

The air-fuel mixture is compressed till the end. Instead of a spark igniting the mixture, the mixture is compressed till the point of self-ignition due to the high compression ratio of compression ignition engines.

The mixture ignites itself and this is how the engine starts!

Reasons Why Your Car Won’t Start Cold (+Solutions)

The cold weather never sits well with automobiles. The engine and engine cycle are designed such that they need a specific ambient temperature for their working.

Following are the main areas of problem that won’t let your car start in cold dark mornings:

  1. Frozen Fuel Lines
  2. Faulty Starter Motor or Alternator
  3. Weak Car Battery
  4. Cold Carbeurators
  5. Wrong Choice of Engine Oil

When cold weather hits, you might face some problems while starting your car. Common problems you will encounter and their solutions are given below:

Frozen Fuel Line

The fuel system plays a vital role if your car has to start in the cold. The correct amount of fuel supply is necessary. The air and fuel are mixed in a certain proportion for the combustion cycle. If the right amount of fuel is not supplied then incomplete combustion occurs.

The products of incomplete combustion are very harmful to the environment.

In extreme cold weather, the fuel injection system of a car is unable to function properly. Similarly, the fuel pump of the car has to work harder in the winter season due to two reasons.

The temperature of incoming fuel is extremely low, so more work is required to raise the pressure of this fuel. Moreover, the parts of the pump become frozen, so to start the process of fuel delivery is difficult in the beginning.

How To Fix:

The quality of the fuel needs to be good in order to avoid starting problems. Some additives are also available for gasoline and diesel vehicles. These additives will lower the freezing point of the fuel and make it more combustible.

If your fuel pump has become too old and it is unable to supply the correct amount of fuel at the start then it needs to be replaced.

Fixing Cost:

The replacement of a fuel pump can cost you between $250 and $800 depending upon the make and model of your car. If your issue is sorted by additives then they are quite cheap. You can get them in the market for $10 to $20 only.

Faulty Starter Motor or Alternator

After battery, two main components of the starting system of a car are the starter motor and the alternator.

A starter motor is also called the cranking motor. Its function is to provide the initial push to the pistons from the rest position.

When you press the ignition button of your car, the starter motor pushes the piston heads and the air-fuel mixture in the cylinder will be compressed. At the end of the compression cycle, this mixture is ignited and the engine cycle is started.

If you have a faulty starter motor, then an initial push cannot be provided, and the car won’t start.

On the other hand, an alternator is responsible for charging the battery when the car engine is running. If the battery is not charged properly, then it will not be able to power the starter motor and spark plugs and the car won’t start.

Though an alternator is also responsible for providing current to the electrical accessories, it is not vital in the starting process of the car.

How To Fix:

The only way to fix a bad alternator or starter motor is to replace it. You need to take your car to a skilled mechanic for diagnosis. If it is confirmed that your car is posing starting problems due to a faulty alternator or starter motor then it needs to be replaced.

Fixing Cost:

Replacement of an alternator can cost you between $500 and $1,000. The cost of a new alternator is around $300 to $700. While the labor cost for alternator replacement is $200 to $300.

Similarly, the replacement of a starter motor can cost you between $200 to $1,450. Nearly, 70% of this amount is represented by the labor cost. The starter motor itself costs no more than $100 to $400.

Weak Car Battery

A weary battery is the leading cause of starting problems in the winter. Even with warm batteries, cold weather does not allow the chemical reaction to take place.

As a rule of thumb, cold batteries simply won’t start. Lead-Acid batteries are based on a chemical reaction in which lead on plates dissolves in the sulphuric acid and ions produce a voltage across battery terminals.

On a cold morning when you have freezing temperatures a bad battery will always cause starting problems.

How To Fix:

There are a number of ways you can deal with battery problems depending upon the type of issue.

You need to check the fluids of your battery properly. In the case of a flat battery, you can try to recharge the battery at a mechanic’s shop. Or with the help of jumper cables and a healthy car battery you can try to jump-start your car.

Fixing Cost:

To jump-start your car you simply need to have jumper cable and battery leads which may cost you $150 to $190 one time only.

If you take your vehicle’s battery to an auto shop for charging, it will cost you $10 to $20.

However, if the battery fails, then you need a new one. A new battery will cost you somewhere between $100 and $200 depending upon the make and model of your car.

Cold Carbeurators

This issue is only faced by the old car that uses a carburetor. The carburetor of a cold car is unable to function properly. The function of air and fuel mixing is compromised. It can cause problems for your car while starting.

How To Fix:

You need to give some time to the carburetor to warm up. Additives are available in the market that will keep your carburetor warm.

Fixing Cost:

No fixing is usually required for the carburetor, only additives will cost you around $10 to $20.

Wrong Choice of Engine Oil

Motor oil with different viscosities are available in the market. The most common ones are 10W40 and 5W30. The first number in the code of engine oil represents the cold viscosity, whereas, the second number represents the hot viscosity.

If you are using the engine oil of high cold viscosity, then chances are that your engine parts will not be able to move easily in winter.

How To Fix:

If your car won’t start in winter due to thick oil then you simply need to use an oil with lower cold viscosity. The best way to go about it is to see the vehicle’s owner’s manual. There you will be able to find a suitable cold viscosity for your engine.

Additives are also available in the market that can make your motor oil thinner. You can try those as well.

Fixing Cost:

You just need to choose motor oil with the correct viscosity that won’t cost you anything. However, the additives can cost you $20 to $30.

How To Start Car in Cold Winter Weather? (Maintenance Tips)

Starting your car in winter is a huge task. If you want to avoid a situation where you face problems while starting the car, then you should follow these winter car maintenance tips.

1. Maintain Your Car Well

The only key to avoiding problems is to maintain your car well. If you are toping up the engine oil in time, battery fluid, and other fluids are checked regularly, then chances of encountering starting issues become very low.

2. Turn Everything Off

Before starting your car on a winter morning, turn off all electrical accessories. Things like windshield wipers, dash lights, stereo, and headlights should be switched off.

3. Avoid Using Weak Batteries

The battery is the main equipment that causes starting problems in winter. You need to have a strong battery before the start of winter.

4. Give Time for Warmup

Do not rush into starting the car. Give the engine some time to warm up. Old cars taking 3 to 5 mins before starting is pretty normal. You need to be patient.

5. Consider Indoor Parking

Never park your car outside in winter. It will let the cold weather sit in the engine. Later this will cause problems for you.

6. Use Breathable Car Covers

Even with indoor parking use breathable car covers. These are special covers that will allow air to pass through, but your car will be safe from scratches, moisture, and snow weather.

7. Use Start Assist Fluids 

If your car is finding it hard to start in the cold, then try using special products like winter start assist fluids. You spray these fluids in the air intake of your car, they will mix with the incoming air, and increase its flammability.

8. Keep Pressing Clutch for Sometime

Try to press the clutch for some time before starting your car in winter. It will get some engine components moving and it will also help in the cranking of your engine.


The worst problem car owners face is when their cars do not start. Especially in the winters when the temperature falls below the freezing point, the dynamics of the engine cycle are changed.

Normal problems that can cause delays in starting are no longer in play. There is a long list of only winter problems that can keep your car from starting.

The basic problem car owners face in winters is the freezing of fuel lines. Though the freezing point of the fuel is below -40 Fahrenheit, it can start to pose problems way before reaching this temperature.

Another common problem faced in winters is dead car batteries. A weak battery or dead battery will not be able to start your car properly.

Similarly, a starter motor and alternator play a crucial role in starting a vehicle. If either of these parts is not functioning properly, it can bar your vehicle from starting on time.

The wrong choice of oil can also cause problems for vehicles in winter.

To cut a long story short, all these problems do have a solution, but you need to diagnose that what is wrong with your car. Only then you can ensure the smooth starting of your car in winter.

Frequently Asked Question

Why my car is not starting in cold weather?

Due to the following issues, your car might not start in freezing temperatures:

1. Fuel System Problems:

Frozen fuel lines, malfunctioning carburetors & fuel injectors are all possible causes of your car not starting in cold weather.

2. Starting System Problems:

Your vehicle’s alternator or starting motor can become defective in cold weather. This can keep your car from starting in the winter season.

3. Battery Related Issues:

Issues with car batteries are very common in the winter season. It is also the leading cause if your car won’t start in winter.

4. Engine Oil Problems:

The wrong choice of engine oil can cause problems for car engines while starting.

Can petrol freeze in a running engine?

No, petrol cannot freeze in a running engine. The running engine has already attained a specific internal temperature. Also, the freezing point of gasoline is very low; hence there are very slim chances that it will freeze anyways.

If you are living in a country where the outside temperature drops below -40 Farenheit then yes, petrol can freeze in your car but only when your engine is not running.

Though the cold temperature can bar the conversion of liquid fuel into gaseous form, this will hinder your car’s starting.

What is the optimum outside temperature for the working of an engine?

Any temperature between 40 and 50 degrees Fahrenheit shall be considered optimum for the engine.

From an engineering perspective, the outside temperature should be as low as possible for the maximum efficiency of the engine.

The higher the temperature difference between the source (high-temperature reservoir, engine in this case) and sink (low-temperature reservoir, atmosphere in this case) higher the efficiency of the engine and vice versa.

But if we consider the vehicle’s starting, then the outside temperature should be as high as possible. It is more suited to the fuel system, cooling system, and starting system of the car.

How to open a frozen car door in cold mornings?

It is very common for car doors to freeze in extreme cold weather. As a temporary fix, you can try to spray an anti-freeze or WD-40 on the frozen door lock. It will melt the snow on it and you will be able to open the door.

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