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Eight reasons your car won't start

Ellie Dyer-Brown, 1 year ago

5 min read

  • Advice
  • warning

Learn about some common reasons your car might be failing to start and how to identify them.

When you rely on your car to get you from A to B on a daily basis, few things spark as strong a sense of dread as when the engine fails to start - especially if you have no idea what’s going wrong under the bonnet.

Why won’t my car start?

Here are eight reasons your car might be struggling to get going:

Man on the phone sitting after a car breakdown

Common problems

My car won't start but the battery is good

My car won't start in the cold

My car won't start with jump leads

My car won't start but has power

My car won't start but the radio works

My car won't start with a new battery

The engine cranks but my car won't start

The immobiliser light is on and my car won't start

My car won’t start but the battery is good

When your car won’t start but the battery works it can be extremely confusing. The most likely culprit is a faulty starter motor, but it’s also worth checking that your battery definitely does work - if the lights and radio still operate it doesn’t necessarily mean that the battery is okay as these electrical systems require much less power than it takes to start the engine.

My car won’t start in the cold

Here are some common reasons your car won’t start in cold weather:

  • Cold battery 

  • Incorrect engine oil

  • Faulty alternator

  • Moisture in the fuel line

You might be able to fix the problem simply by restarting your car. Switch the engine off first and then dip your clutch during ignition. If this works, let your car run for several minutes before trying to use the heater or any electrical equipment. 

Still unable to start your car? Try the following:

  • Check your engine oil and top up as necessary

  • Check all battery cables and terminals

Once you’ve determined that you have the correct level of engine oil and your battery looks healthy, the next option is to try jump starting your car. Find out how here.

Failing this, call a local mechanic who will be able to diagnose the problem and get you back on the road in no time.

My car won’t start with jump leads

There are three main reasons your car won’t start with jump leads:

In all of these situations you’ll need the help of a mechanic to make your car work as it should (unless you feel confident replacing a dead battery yourself). 

Jump Starting Car in Winter

My car won’t start but has power

If the engine turns over but won’t start, it’s likely you’ve got a flat battery. Frequent starting problems indicate that your battery could be corroded or damaged and needs to be replaced.

My car won’t start but the radio works

The fact that your car’s radio still works should be viewed as a positive sign because it indicates the problem is simply a flat battery rather than anything more serious. Often, flat batteries are still able to power electrical components like the radio because these require less power.

In this instance, jump starting your car is likely to solve the problem. Find out more about what to do when your car battery is dead here.

My car won’t start with a new battery

There are two potential reasons that your car won’t start with a new battery.

The first is that your battery hasn’t been fitted correctly or one of the terminals is loose. This guide explains how to change a battery and can be used to check that your current battery is properly installed.

My car won't start right away after getting gas

If your car won't start even after you've just filled up the fuel tank you might be looking at a faulty fuel pump or fuel injectors. This will require specialist attention - fortunately, WhoCanFixMyCar can help you find a reliable local garage or even a mobile mechanic.

To test whether this is the case, try starting your car as if the engine is flooded next time you fill up. Find out how to restart a car when the engine is flooded here. If this works, there's probably something wrong with the system in your car that's responsible for moving fuel from the tank into the engine.

The engine cranks but my car won’t start

The fact that your car is able to crank suggests that the problem is with the battery, which, fortunately, is a relatively easy fix. You should be able to solve the problem by jump starting the car

Battery and oil light on and car won't start

The fact that both your battery and oil engine warning lights are on suggests that there could be multiple issues with your car which are impacting its ability to start.

Firstly, check your engine oil level. If it's too low, top it up and look closely to see if you can spot any leaks. In the event that there is a leak, you'll need to take your car to a garage as soon as possible to have it repaired.

Next, check your battery. Can you see any signs of corrosion or damage? Are the terminals connected properly? If your engine turns over but won't start, you probably have a flat battery. You can try jump starting the vehicle, but if the engine warning lights stay on you should have it checked by a mechanic.

The immobiliser light is on and my car won’t start

It’s likely that there’s some kind of fault with either the engine immobiliser or the key transponder causing the warning light to come on and your car not to start. You’ll probably notice that your car starts up for a few seconds only to turn off again. 

The best course of action in this situation is to have your car’s immobiliser system looked at by a professional who will know exactly what is going wrong.

Why your car won't start - explained

Flat or faulty battery

Battery problems are one of the most common causes of breakdowns. Unsurprisingly, they’re also the most common reason that a car won’t start. In this case, you might hear a repeated clicking sound when you turn the key.

There are a few factors that influence how well (or if) your battery functions:

  • Lack of use

  • Electrical feature left on in the car

  • Repeated short journeys

  • Age

In this situation, you might be able to use a jump start to get back on the road, but you should have your battery checked by a mechanic to determine whether it needs replacing. 


Find out how to maintain your car battery to prevent future problems here

Fuel problems

Having an empty fuel tank is one thing that’s easily solvable, but there are a number of other problems that could be at play. 

For example, your fuel pump may be faulty or there could be mechanical issues with the fuel system. To solve these, you’ll need to make a trip to your local garage for repairs.

Have you accidentally filled up with the wrong fuel? If so, don’t drive your car as you could end up causing damage to the engine. Instead, find a local garage or mobile mechanic who will be able to drain your tank and fill it with the correct type of fuel.

For more information about what happens when you fill up with the wrong fuel, check out our guide.

Starter motor

The starter motor is connected to the battery. It’s responsible for moving the engine when you turn the ignition. If you hear a loud clicking sound when you turn the key, this indicates that the starter motor might be at fault.

Contact a local garage or mobile mechanic who will happily get you back on the road in no time.

Clogged fuel filters

It’s no surprise that when a car’s fuel filters become clogged the vehicle will struggle to start. This is because petrol or diesel can’t reach the engine, preventing combustion from taking place.

Filling Up with Petrol

Fuel filters are usually replaced during a full service; the best way to prevent blockages is to service your car regularly.

Alternator problems

The alternator plays an important role not only in recharging the battery, but also in powering the car’s lights, radio and heating. Consequently, you can usually tell when your alternator is on the way out because you will likely experience symptoms such as dim lights and frequent stalling.

If you think you might need a new alternator, WhoCanFixMyCar can help you find the right garage at the right price. Click here to get quotes.

Flooded engine

This applies particularly to petrol engines which have been switched off too soon after starting in the cold. As a result, unburned fuel remains in the system and wets the spark plugs, making it almost impossible for the car to start.

A whirring or cranking sound when you turn the key signals a flooded engine.

Jammed ignition lock

If you can’t turn your key in the ignition, your steering lock could be jammed. Fortunately, this is an easy do-it-yourself fix. One of your front tyres is probably jammed up against a kerb, so in order to free it, simply move your steering wheel from side to side while turning the key back and forth.

Starter motor

Engine intake problems

Problems of this kind include faulty throttles, fuel injectors, regulators and sensors. These can be complicated to fix so it’s best to find a reliable local mechanic who can do it for you. 

Whining and sputtering sounds often indicate engine intake problems.

Now you know why your car might not be starting, find out what to do about it here.

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