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The 10 most common breakdown causes

There are a variety of common reasons why a car breaks down at the side of the road. Here’s a look at some of the most common causes of breakdown and what you can do to minimise the risks…

There are a variety of common reasons why a car breaks down at the side of the road. Here’s a look at some of the most common causes of breakdown and what you can do to minimise the risks…

Written by
Julie Daniels
Motor insurance expert
Last Updated
3 JANUARY 2023
7 min read
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1. A flat or faulty battery

Battery trouble is often the main cause of breakdown issues.

You may well have a worn-out or flat battery if your car:

  • Struggles to turn the engine over
  • Takes longer than usual to start
  • Doesn’t start when you turn the key
  • Displays the red battery warning light while you’re driving. 

Regular driving is important for keeping your battery charged, but short journeys often don’t provide enough power. Charging the battery overnight every so often might help extend its life. You can do this using a trickle charger, which slowly recharges your battery.

Remember though, batteries don’t last forever – they usually last around five years.

See more on looking after your car battery.

2. Alternator faults

The alternator helps generate power for your car’s electrics: without it, the battery can’t be charged up by the engine. While your battery’s stored power is enough to keep the electrics running for a while, if your alternator stops working, your battery will eventually go flat.

There’s no specific way to maintain your alternator, but if you notice the car’s power isn’t what it should be – such as dimmed headlights, slow wipers, or flickering dashboard lights – or your ignition warning light comes on, stop and get assistance.

3. Damaged tyres or wheel

A flat tyre caused by a puncture is a very common cause of breaking down. If an unseen pothole or debris on a road surface damages your tyres or wheels, there’s not much you can do except stop and check for damage. 

However, poorly maintained tyres are more likely to have issues. Check your tyres regularly, making sure they have a tyre depth of at least 1.6mm and they’re inflated to the right tyre pressure. While you’re at it, look for patterns of wear. An uneven wearing of the tyres could indicate that your wheels aren’t aligned properly. 

Modern cars don’t always come with spare wheels, but if you do have a spare tyre, make sure it’s in the same good condition as the other four, and that your jack and any locking wheel nut keys are stored with it ready to use in an emergency.

4. Electrical problem

Your car’s electrical system includes a range of circuits controlling everything from the headlights to the stereo. Problems can crop up thanks to burned-out bulbs, faulty wiring, blown fuses or wear and tear.

Although it’s possible to track down where the fault is by using a multimeter and a little detective work, if it’s not an obvious issue like a blown bulb, you may want to ask an expert for help. A trained mechanic can run a full analysis of the electrical system and advise you on what to do.

5. Keys and alarms

Though it’s harder to lock our keys in the car than it once was thanks to central locking, it’s not impossible. With alarms and immobilisers getting more sophisticated than ever, many people have to call for help when they can’t get into their own cars.

These days, car keys often include a microchip, which is designed to stop your car being stolen – another good reason to keep a spare somewhere safe in case you lose it.

6. Misfuelling

If you’ve ever made the mistake of putting the wrong fuel in your car, you’re not alone. Thousands of distracted Brits have a misfuelling calamity every year. 

If you’ve accidentally put petrol in your diesel car (or diesel in your petrol car), the quicker you act, the better. If you don’t start the engine, you’ll probably just need to have the fuel pumped out and replaced. 

If you’ve started the engine or driven any distance after misfuelling, things become a little more complicated. In some cases, getting the fuel being pumped out and the system flushed might do the trick but, in others, mechanical damage can be caused and might require further work.


7. Clutch cables on manual vehicles

If you’re driving a manual car, the clutch cable comes under pressure every time you change gear. If you notice any difference in the way the clutch feels under your foot, don’t ignore it. Get your car to a garage and have it checked. If the cable breaks while you’re driving, pull over in a safe place and call assistance.

8. Diesel Particulate Filter (DPF)

Diesel engines are fitted with a special filter that traps dirt and fine particles of soot and burns them off, reducing harmful exhaust emissions. If you use your diesel car for a lot of short journeys, the DPF filter can get blocked.

In order to ‘regenerate’ and clear the filter, diesel vehicles need a good run every now and then. A weekly run up the motorway for a decent period should stop the DPF from blocking.

9. Starter motor 

Thanks to stop/start technology, starter motors have to work harder than ever. Although robust and durable, they can eventually fail. If your battery is fine but the engine doesn’t turn over when you push the stop/start button, it’s most likely a starter motor problem.

Regular servicing and maintenance is the best way to avoid starter motor problems – and the need for home start help.

10. Overheating 

Overheating is a common problem if you’re sitting in heavy traffic, especially in hot weather. Keep a regular eye on your coolant level and fan to make sure your cooling system is working as it should. If the temperature warning light comes on, you’ve got a problem. Modern coolant systems shouldn’t need topping up between services, so if the level has dropped you may have a leak which will need to be checked out.


Did you know…? 

Breakdown providers typically prioritise customers in vulnerable situations and make an effort to get to them first – for example, elderly drivers, women alone on remote roads or drivers with young children. So, a driver with young children stranded on the hard shoulder of the motorway should get priority over a ‘home start’ rescue for someone sitting on their driveway at home.

Top tips for avoiding a car breakdown 

Breaking down is one of the most frustrating problems that all drivers dread. So, rather than beating your car with a stick while waiting for help to arrive, follow our handy tips to help you avoid a breakdown in the first place: 

  • Never miss a service – a regular service ensures your car stays roadworthy, and means that any faults or issues can be dealt with before they escalate into serious problems. You should also make sure your car has a valid MOT.
  • Drive properly – the way you drive can have a direct impact on the health of your car. Avoid hard stops and starts, revving your engine in cold weather and crunching the gears or riding the clutch. Brake smoothly to avoid putting strain on the brake pads which will eventually wear down. 
  • Don’t overload your car – excessive weight means your car needs to work harder and your suspension and brakes will be put under more stress. Clear out the clutter and hire a van if you need to transport heavy items like furniture.
  • Don’t ignore warning lights – they’re there for a reason. If a warning light comes on, you have a problem that needs to be checked out. Ignoring it means you’ll be dealing with bigger, more costly repairs further down the line.
  • Be aware of strange noises – if your car starts making strange noises or feels different to drive, get it checked out straight away. Ignoring the issue won’t make the problem go away, and things will only get worse over time. For example, if your car has trouble starting or has a lack of power, you might need to replace the spark plugs.

And finally, take out breakdown cover, so if you do end up unexpectedly stranded, roadside assistance is on the way to get you back on the road as quickly as possible.

Add some peace of mind to your travel plans.

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