What to Do When Your Car Won't Start

When your car won't start, it can ruin your day pretty quickly. Most of us will face this at some point in our lives, whether we're a driver or a passenger, so it's worthwhile familiarising yourself with what to do.

Reasons your car won't start

Here are a few of the most common reasons.

1. A flat battery

A flat battery is one of the most common reasons a car won't start. It can happen due to old age, a broken alternator, or leaving the lights or electrical systems running while the engine is off.

What to do

You have a few options:

• Try performing a jump start - this guide explains how.

• Call your breakdown cover provider.

• Contact a mobile mechanic who can test whether the battery needs replacing and, if so, do the job wherever you are.

• Replace the battery yourself - find out how.

The average price of a battery replacement on FixMyCar is £234.82.

2. Broken starter motor

Can you hear a single, loud click when you turn the key in the ignition? If so, you may be experiencing a problem with the starter motor.

What to do

You'll need to contact a mechanic for this one. The average price of a starter motor replacement is £392.02.

3. Stuck steering lock

If you can't turn the key in the ignition, the steering lock might be jammed, which typically happens when one of the car's front tyres is wedged against a kerb.

What to do

You should be able to free the lock by moving the steering wheel slightly from side to side while trying to turn the key. If you can't move the wheel at all, push the brake pedal and slowly release the handbrake to let the car roll away from the kerb a little. Then, put the handbrake back on and try again.

4. Immobiliser

Your car's security system could be the thing preventing it from starting. If the immobiliser doesn't recognise your key, the engine won't start. This often happens due to a flat battery in the key fob.

What to do

The first thing to try is replacing the battery in the key. If that doesn't work, your key may need reprogramming, which is a job for a car locksmith.

The average price of an auto locksmith repair is £188.91, according to our data.

5. Fuel system issues

Several fuel system issues could prevent your car from starting, including a broken fuel pump and a blocked fuel filter. Unfortunately, there's no easy way to diagnose these problems.

What to do

If the fuel system is to blame, you'll need the help of a mechanic. The average price for this kind of repair is £244.86.

6. Flooded engine

Flooded engines aren't very common anymore because of the fuel injection system fitted to modern cars. When an engine is flooded, there is too much fuel and not enough air in the combustion chamber. It typically happens when a car is switched off too soon after starting.

What to do

Follow the advice in this guide to start a car with a flooded engine.

7. Spark plugs

Spark plugs need replacing every 100,000 miles or so. When they wear out, the engine might not start. Learn about the other signs of spark plug failure in this guide.

What to do

You can either change the spark plugs yourself or find a local mechanic to do the job for you. On average, a spark plug replacement costs £159.17.

8. Faulty alternator

The alternator charges your car's battery and powers the electrical systems. When it stops working, the battery will eventually go flat and the vehicle won't start.

Here are five signs of a faulty alternator.

What to do

Some alternator problems, such as a loose belt or faulty diode, can be repaired. Others require a replacement. Contact a mechanic who can advise you about the best course of action.

The average price of an alternator repair on FixMyCar is £533.64.

9. Low AdBlue

AdBlue is a fluid added to diesel cars to help lower emissions. You can learn more about how it works here. When you run out of it, your car won't start again and may require the help of a mechanic since some models need software to get going.

What to do

The best thing to do is avoid running out of AdBlue by paying attention to the dashboard warning that the tank is getting low. However, if you do run out, try topping it up first, and if that doesn't work, call a mechanic.

What to do if your car won't start

If you find yourself broken down at the roadside with a car that won't start and you can't find a way to fix it, you'll need to focus on staying safe, follow the procedure in this guide, and call for help from your breakdown cover provider or an emergency car recovery company.

Here are our top tips for avoiding a breakdown.

Frequently asked questions

Still can't get your car started? We'll help you find a local mechanic to get you back on the road in no time.

If you found this guide helpful, you might also like:

• Eight reasons your car won't start

• What to do when your car battery is dead

• How much does it cost to repair a starter motor?

• When do the spark plugs in your car need replacing?

• How to jump-start a car

• Car ownership 101: everything you need to know