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Top 10 most common causes of car breakdowns

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Car breakdowns are rare, but the chances are higher during the winter months.

We’ve analysed internal data to compile a list of the most common reasons for vehicle breakdowns. There are also top tips to help keep you safe - and your car on the road.

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If you're an Admiral customer, call our customer services team to discuss the different levels of cover we offer. Your cover will start 48 hours later. Or you can buy our Breakdown Cover when you get your car insurance quote.

1) Battery


The fact that battery failure is the most common cause of people’s cars breaking down shouldn't come as too much of a surprise - particularly during the winter.

A variety of reasons can cause a flat battery including a loose terminal connection, a fault with the battery itself, leaving the lights on - or simply old age. Leaving your car unused for a while, or only using it for short journeys might also be a cause, especially in cold weather when the battery is under more strain than usual. It's also worth remembering that there might be a problem with your car's starter motor or the alternator, which recharges the battery.

Top tip: Most car batteries have a guarantee of 3 to 5 years, so if you have an old battery and it’s starting to struggle, replace it before it lets you down.

2) Tyres


It would be unusual for you to go through your car ownership lifetime without experiencing a flat tyre.

Punctures can be caused by hitting a kerb or pothole, running over a sharp object like a nail or screw, a faulty valve or simply a worn tyre tread. The best way to avoid tyre failure is to check the pressures and tread condition of each tyre regularly and don't ignore the tyre pressure warning light if it appears on your dashboard.

Top tip: Always carry a correctly inflated spare tyre (full size or space saver). If that's not possible, make sure you have an emergency puncture repair kit. The aerosol contains a foam which re-inflates the tyre and acts as a sealant. Preferably, choose one with a water-based foam that can be flushed out after use and doesn't damage the tyre.

3) Engine and exhaust


This is perhaps the most wide-ranging reason for a car breakdown and includes just about everything that can go wrong in an engine bay. So, think cylinder head gasket, timing belt, oil pump failure, oil leaks and ageing spark plugs, plus faulty fuel and ignition systems.

There may also be issues with your exhaust system, such as corrosion, cracks, broken brackets and increased levels of pollutant gases. Additionally, the catalytic converter, or CAT, forms part of the exhaust system. Its job is to clean up the harmful gases emitted from your engine before they can escape through your exhaust pipe.

Top tip: Keep up with routine maintenance jobs and stick to your car's service schedule (usually a full service every year). Remember, a well maintained car will not only have a longer life, but it's also likely to be safer and more reliable. 

4) Electrical


One of the big downsides of the increased technology in modern cars is that there's more to go wrong. Electrical problems can be some of the most frustrating reasons for a vehicle breakdown because the reason is not always obvious.

Often, cars must go to a garage where mechanics can carry out a fault diagnosis by hooking up to the car's onboard computer (the electronic control unit, or ECU) and read error codes. Electrical problems can range from something as a simple as an interior or exterior bulb failure, to worn out spark plugs, or a faulty starter motor or ECU.

Top tip: Never ignore dashboard warning lights - they are your first line of defence against a potentially large garage bill. If you're unsure what a light means, pull over when it's safe to do so and check your owner's manual. If it's serious, seek immediate help from your breakdown provider or a garage.     

5) Steering, suspension and brakes


Again, a wide-ranging category when it comes to reasons for vehicle breakdowns. Steering defects include issues with power steering units (including fluid leaks), plus worn components in the steering rack. Faulty dampers, or shock absorbers, are one of the most common failures in a car's suspension system.

Sometimes it's just wear and tear. However, it's also possible that the fluid has started to seep out. Brakes are another crucial car component. Ignoring any problems can have serious consequences, putting you and other road users and pedestrians at risk. Warning signs includes brakes pedals that feel soft, spongy or offer no resistance. Your car may also pull to one side, or you can feel a vibration through the steering wheel. The problem could be anything from worn pads or discs, or a fluid leak from the master cylinder. Whatever the problem, don’t take any chances. Get expert advice.

Top tip: Your brakes will be checked during your car’s annual service and MOT. However, some garages and tyre-fitting chains will also carry out free brake checks.

6) Fuel


Accidentally filling up your car with the wrong fuel is more common than you might think, affecting an estimated 150,000 motorists every year. We have lots of advice to help you avoid this potentially disastrous mistake - whether it's putting petrol in a diesel car or diesel in a petrol car. Embarrassingly, running out of fuel is another reason for roadside rescues. Other fuel-related faults which can cause a breakdown include problems with the fuel pump and the throttle assembly, plus blocked fuel injectors and filters.

Top tip: If you misfuel your car, the worst thing you can do is panic. If you're lucky enough to realise you’ve put the wrong fuel in your car before starting your engine, leave the engine switched off (don't even put your key in the ignition) and inform the staff at the service station.

7) Clutch


If you drive a manual car, the clutch plays a crucial role, enabling you to smoothly change gear. However, over time, a clutch can wear out or the system may develop a leak. Warning signs include a clutch pedal that feels spongy or makes an unusual noise. You may also rev the engine, but find the acceleration is poor, or you have difficulty shifting gears. You might also experience a 'slipping' clutch, which causes a momentary loss of acceleration. A clutch should last anywhere between 60,000 to 80,000 miles - longer if you treat it with respect. Clutch components include the clutch plate, pressure plate, flywheel, slave cylinder and clutch cable.

Top tip: Never 'ride the clutch'. In other words, don't keep the clutch pedal partially pressed down because it pushes the pressure pad against the clutch plate but doesn't engage completely, therefore creating more friction and wearing out the clutch faster. Instead, keep your foot well away from the clutch unless you are actually changing gear. Don’t slow down for traffic lights with the clutch semi-depressed and don't treat your clutch pedal like a footrest.

8) Alarms, locks and keys


Faulty alarms aren't just a nuisance for you and your neighbours, they can also trigger the immobiliser which means you are going nowhere. If you're having issues with the car alarm, your first port of call is to change the battery in your fob. If that doesn't work, there may be a fault with the fob itself. If so, try your spare fob. It could also be an electrical problem with a sensor, in which case you should get professional help.

Breakdown services have also been called out for keys locked inside vehicles, broken keys and keys stuck in ignitions, plus jammed steering locks.

Top tip: Losing keys can be a costly mistake. If possible, avoid buying a new key from a main dealer (it could cost as much as £150-£300). Instead, get a replacement from a key cutter like Timpson, or get a quote from a mobile auto locksmith.

9) Charging


We've already mentioned the alternator, which charges the battery, in our No 1 cause of vehicle breakdowns. Related alternator components include the drive belt, the pulley and the battery warning light which warns you when the alternator is not charging the battery.

Top tip: An alternator can go at any time. Signs that all might not be well include the dashboard warning light, flickering headlights, plus a grinding, clanking or screeching noise coming from your engine bay.

10) Cooling


Traditionally, overheating has always been one of the top causes of a car breakdown. You might notice your temperature warning light go on or, worse still, steam coming out of your engine bay. Either way, pull over in the nearest safe spot, turn off your engine, get all passengers away from the car and road, and call for breakdown assistance.

If you're more confident mechanically, open the bonnet (it may be hot) and leave the engine to cool down for 30 minutes or so. Once it's fully cooled, carefully check the coolant. Never unscrew the radiator/coolant tank cap of an overheated engine - it's pressurised and it could cause severe burns. If there's no coolant you probably have a leak (possibly in the radiator or a hose) and there may be a pool of liquid underneath your car. Other reasons for an overheating car including a faulty thermostat, cooling fan or water pump.

Top tip: Avoid overheating by regularly checking and topping up the coolant. Also make sure the cooling fan is operating - you can hear it after a journey. Also look under your car now again to check for any leaks.

I'm an experienced journalist, digital editor and copywriter, now specialising in motoring. I’m editor of Automotive Blog and have worked across the media in newspapers, magazines, TV, teletext, radio and online for household names including the BBC, GMTV, ITV and MSN. I’ve produced digital content in the financial sector for Lloyds Bank, Nationwide and the Money Advice Service. I'm married with two children and live near Bath in Somerset.

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