Which? uses cookies to improve our sites and by continuing you agree to our cookies policy

Five car faults most likely to affect you

Common problems and the cars that suffer from them

Broken down car

Got a problem with your sat nav, parking sensors or exhaust system? You’re not alone. These are among the most common car faults you’re likely to experience, according to our survey.

Buying a new car is a fantastic luxury. You stroll out of the glitzy showroom having elegantly applied your signature to all the paperwork, ease yourself into a car that has not had any previous owners and find yourself light headed on that ‘new car’ smell. And then, soon after, the sat nav goes on the fritz.

While it’s unlikely your car will develop a fault on the way home from the showroom, even cars in their first few years of life can suffer from faults that will have you trudging back to the garage for a fix.

Then, while the best cars age gracefully, others prove cantankerous before their time, providing their owners with a steady stream of annoying faults and more serious breakdowns.

What follows was revealed by our 2016 car survey. Fill in the 2017 Which? Car Survey to help us keep our reliability data up to date – and be in with a chance of winning £2,500.

Most common faults in cars aged three years or less

You would expect a young car in the prime of its life to be fairly immune to all faults, but sadly it’s not the case. We can reveal that the top-five faults largely focus around the car’s electrics:

  • The sat nav
  • Factory-supplied in-car entertainment
  • Lights/light units
  • The exhaust or emission control system
  • Tyre pressure sensors

Most common problem in newer cars: sat nav


As it’s the most common fault, having a dodgy sat nav is a problem shared by many different cars on our roads. However, the survey shows that the three cars most likely to suffer from it are the Suzuki SX4 S-Cross, Hyundai i40 Tourer and Ford Mondeo Estate.

Here’s what a few Suzuki SX4 S-Cross owners had to say about their experience:

‘Software crashes intermittently, losing presets, and the sat nav seizes up when driving, requiring a reboot.’

‘The in-car sat nav is poor, expensive to maintain/update when it should be free and gets it wrong too often. In a £20k+ car that is not acceptable.’

Most common faults in older cars

All cars age, but the best will do so with only minor ailments – though naturally it will partly depend on how well they’ve been maintained over the years. These are the top five areas where cars between three and eight years old will suffer faults:

  • Battery
  • Exhaust or emission control system
  • Lights/light units
  • Brake pads and discs
  • Air conditioning
  • Suspension components

Batteries and brake pads naturally have to be replaced with common wear and tear, so we’ve included the sixth most frequent fault in our list – problems with the suspension.

Common problem: issues with the exhaust/emission control system

Exhaust pipe

One of the most potentially serious problems listed above is a problem with the exhaust or emission control system. 30% of owners that suffered from these faults told us their cars were off the road for two days or more as a result.

Again, as it is a common problem, many older cars share this fault. But when we ran through our data, we found that owners of the diesel versions of the Honda Accord (2008-2015) and Ford C-Max (2003-2010), and petrol versions of the BMW 1 Series hatchback (2004-2011) were most commonly affected by these problems. 

Complaints from owners of these cars include:

‘Annoying intermittent problems with the EGR valve.’

‘The diesel exhaust filter gets clogged on too many short trips, which is expensive to fix.’

Problems with diesel filters

It’s worth noting that diesel particulate filters (DPFs) are prone to being clogged if you only use a diesel car primarily for short journeys, and it can be an expensive fix.

The better fuel economies offered by diesel-powered cars can make them look tempting over petrol equivalents. But given the premium for diesel engines, the current scrutiny over emissions and problems that can occur with diesel-powered cars, you might want to think again.

For more information, comparative diesel and petrol costs and our handy fuel cost calculator, check out our guide to choosing between petrol and diesel.

More on this…

Back to top