At a glance
The most common car breakdown causes include a flat or faulty battery, tyre damage and alternator issues.
Other culprits are fuel problems, starter motor failure and engines overheating.
Electric cars can be prone to software glitches and battery problems.
To prevent car breakdowns, get an annual service and don’t ignore warning lights.
1. A flat or faulty battery
Battery trouble is the number one cause of breakdown issues, especially in winter. 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.
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 have a lifespan of around three to 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.
Signs of a faulty alternator include:
Dimmed headlights
Slow wipers
Flickering dashboard lights
A loud grinding noise when travelling at speed
A dashboard warning light.
If you ignore these signs, the engine could cut out at any point, causing the car to break down suddenly.
3. Damaged or flat tyres
A flat tyre caused by a puncture is a common cause of breaking down. If a 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.
Poorly maintained tyres increase the risk of blowouts. Check your tyres regularly, making sure they have a tread depth of at least 1.6mm and they’re inflated to the recommended tyre pressure.
While you’re at it, look for patterns of uneven wear. These could indicate that your wheels aren’t aligned properly.
Ideally, you should always carry a correctly inflated spare tyre or puncture repair kit with you, so you’re prepared if the unexpected happens.
4. Electrical problems
As cars get more advanced, electrical problems are becoming more common. Circuits control everything from the headlights to the infotainment. Problems can crop up thanks to burned-out bulbs, faulty wiring, blown fuses or wear and tear.
Electrical problems can be hard to diagnose and fix at the roadside, so be sure to check out any unusual symptoms before they cause a breakdown.
A trained mechanic can run a full diagnostics analysis of the electrical system and advise you on what to do.
5. Running out of fuel
If you’re one of the 10 million motorists who let their tank get as close to empty as they dare before refuelling, don’t be surprised if your luck runs out one day.
Running out of fuel is an increasingly common cause of breakdowns as drivers go to extreme lengths to budget. If you suddenly grind to a halt before making it to a petrol station, pull over to somewhere safe.
Resist the urge to keep trying to restart the engine as this can suck air and dirt from the empty tank into the fuel system. This will make starting your car even more difficult once you’ve filled up.
If you have breakdown cover, call your provider. Most policies include delivery of enough fuel to get to a petrol station, although you’ll be charged for the fuel itself.
6. Keys and alarms
With alarms and immobilisers getting ever more complex, things can easily go wrong with car keys and sensors.
From key fob faults and keys locked in cars to jammed steering locks, there are many reasons why people have to call for assistance.
To help avoid key-related breakdowns, keep a spare somewhere safe.
7. 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 pumped out and the system flushed might do the trick. But, in others, it might have caused mechanical damage.
8. Clutch failure
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, or your car seems to ‘rev’ when accelerating, there could be a problem.
If the cable breaks while you’re driving, you won’t be able to change gear. Pull over in a safe place and call for assistance.
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 are the best ways to avoid starter motor problems – and the need for home start help.
10. Engine 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.
Common breakdown issues for electric cars
It’s not just petrol and diesel cars that break down. Although electric cars have fewer moving parts to go wrong, they can have issues including:
Battery failure – EV batteries last around 10 years but can degrade over time. This can be hastened by frequent fast charging, extreme temperatures or charging beyond 80% too often.
Software glitches – EVs rely heavily on electronic control units to manage everything from battery temperature and steering to infotainment. These can cause various issues, from frozen touchscreens to the car being unable to start.
Tyre and suspension problems – EVs are heavier than petrol and diesel cars because of the battery. This can make them more susceptible to damage from potholes and road debris.
Charging faults – if your EV is struggling to charge, it might not be the battery that’s the issue. Problems with charging cables, connectors or public charge points could be to blame.
When electric cars do break down, they’re less likely to be fixed at the roadside than petrol or diesel cars, according to What Car? research. But as they become more mainstream, this is likely to improve.
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.
Top tips for avoiding a car breakdown
All drivers dread something going wrong with their vehicle. Follow our handy tips to help you avoid a breakdown in the first place:
Never miss a service – a regular service helps your car stay roadworthy, and means that any faults or issues can be dealt with before they escalate into serious problems. You must also make sure your car has a valid MOT.
Drive smoothly – 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.
Avoid overloading 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 such as 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 likely means you’ll be dealing with bigger, more costly repairs further down the line.
Be aware of strange noises – if your car starts making unusual noises or feels different to drive, get it checked out straight away. 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. If you do end up unexpectedly stranded, you’ll have the reassurance that help will soon be on the way to get you back on the road as quickly as possible.
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With more than eight years’ experience in writing and sub-editing content, Karen started her career in fashion before making the move to insurance. She now specialises in producing clear, engaging content that helps people make better financial decisions.
Karen’s areas of expertise include insurance products, such as car insurance, travel insurance and life insurance, as well as utilities such as energy comparison.
Stephen Maunder is an experienced personal finance editor, having spent more than a decade working for consumer print and online titles. He won several industry awards for his personal finance features at Which?, before becoming Deputy Editor at Compare the Market.
Amy helps make sure you get the best value when choosing insurance. Thanks to more than four years’ experience at Compare the Market, she understands what people look for, working closely with insurance providers to offer you deals and services that are fair, easy to understand and right for your needs.
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