Car computer breakdowns double as drivers face a new motoring headache
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Increasingly sophisticated car electronics are creating a new headache for drivers, with computer-related breakdowns doubling since 2020.
If your car suddenly refuses to unlock, the lights stop working or several electrical systems start behaving erratically, there could be a surprisingly modern reason… Your car’s computer could be having a meltdown.
Breakdowns involving a vehicle’s Body Control Module (BCM) have doubled since 2020, with more than 36,000 incidents now recorded each year, according to the AA.
The rise means computer-related problems have entered the AA’s top five causes of breakdowns – although they remain considerably less common than more familiar issues such as flat batteries and damaged tyres.
Here are the top five reasons for AA callouts between 1 July 2025 to 30 June 2026:
- 12V battery
- Tyres
- Engine/Clutch
- Alternator/Start motor
- Body Control Module
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What is a Body Control Module?
The BCM might not be something you’ve ever heard of, but it plays a major role in many modern cars.
Think of it as one of the vehicle’s electronic control centres. It can manage functions including lights, electric windows, windscreen wipers, alarms and central locking.
So when the BCM develops a fault, it can look as though several different parts of the car have suddenly stopped working. This can leave many drivers wondering what on earth has gone wrong.
Why do car computers fail?
There isn’t necessarily one obvious culprit.
The AA says BCM problems can be caused by driver error, problems with the chip in a key, damage, poor garage work or an electronic glitch.
Even trying to jump-start a flat battery can potentially cause problems if the leads are connected incorrectly.
AA mobile mechanic Joe Morbin said: “While it’s easy to blame the computer, there’s often some kind of human error or action that has contributed to the fault.”
He warned that incorrectly connecting jump leads can cause serious damage to the BCM.
“Electronic faults can be difficult for drivers to understand and we’re seeing more cases where a single control module affects several vehicle systems at once.”
That can make diagnosing the problem particularly frustrating for motorists who aren’t familiar with the electronics hidden beneath the bonnet.
You don’t always have to get the car to a garage
For drivers who discover an electrical fault on their driveway, the traditional solution would be to arrange recovery and get the car to a garage.
But the AA says more motorists are turning to at-home diagnosis and repair instead.
Its Fault Finder and Mobile Mechanic services can come to a customer’s home or workplace to investigate problems.
The Fault Finder service costs £99 per visit, with the AA saying around one in four problems are fixed quickly at no extra cost.
If a more complicated repair is needed, the driver can discuss the options with the mechanic.
The services are available to AA members and non-members.
Morbin said the services are becoming increasingly useful as cars become more dependent on electronic systems.
“Whether it’s a warning light, a suspected electrical fault or preparing for the return to school, having your vehicle checked at home or work can help reduce unwanted disruption,” he added.
A warning for drivers heading back to the school run
With the summer holidays drawing to a close, the AA is encouraging motorists to give their cars a quick check before getting back into the routine of regular commuting and school runs.
AA president Edmund King said drivers have become used to having everyday services brought to their homes – and that vehicle maintenance is increasingly following the same trend.
“People are now used to the convenience of home shopping, food deliveries and even working from home, so The AA is now offering home servicing and a fault finder service on people’s driveways.”
He added that checking a vehicle before a journey could help drivers avoid discovering a problem when they need the car most.
“Modern cars are increasingly reliant on electronics, so identifying a fault on the driveway is far better than discovering it when you need to get somewhere.”
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