Car tech computer confusion has become one of the UK’s top five causes of breakdowns, the AA reveals.

Whilst people might be used to ‘computer says no’ at home or work, many are being flummoxed by the technical complexity of their vehicles. However, drivers can be reassured as the AA’s new ‘IT support’ in the guise of mobile mechanics can now come to drivers’ homes or offices to sort out these problems.

Computer breakdowns

Since 2020, breakdowns related to the Body Control Module (BCM) have doubled to more than 36,0001 a year. This is the onboard computer that acts as the electronic hub for many vehicle systems, including lights, windows, wipers, alarms and central locking. When a BCM develops a fault, multiple systems can be affected at once, often with little warning.

Driver error, something wrong with the entry key chip, damage, botched garage work or a computer glitch are some of the reasons why the BCM may decide to play up. Compared to the major causes of breakdowns, such as tyres and batteries that are counted in their hundreds of thousands of incidents each year, these faults are not as common but are rapidly increasing.

	Top five reasons for AA callouts between 01/07/2025 – 30/06/2026
1	12-volt battery
2	Tyres
3	Engine / Clutch
4	Alternator / Starter motor
5	Body Control Module

Mobile mechanics

While AA Home Start covers millions of AA members at home for this type of scenario, there are many car owners without this cover who climb into their vehicles on the driveway or outside their homes and discover that the computer has gone on strike.

Faced by having to get the vehicle to a garage and then having to wait until it can be looked at, the AA now offers a Fault Finder option as part of its Mobile Mechanics service. This brings mobile garage repairs and servicing to homes or work and is available to all vehicle owners whether AA members or not.

Costing £99 a visit, experience has shown that one in four problems are quickly fixed at no extra cost. With more complicated problems, the car owner can discuss options with the mechanic to decide how to fix the fault in a way that suits the owner.

While it's easy to blame the computer, there's often some kind of human error or action that has contributed to the fault. AA Mobile Mechanics are hand-picked for their technical expertise and problem-solving skills. Many have also joined us from our roadside patrol force, bringing with them years of experience diagnosing and repairing complex faults at customers' homes.

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. One of the common causes is when someone tries to jump-start a car and attaches the power leads incorrectly. That will often kill a BCM stone dead.

It is the reason why at-home services like Fault Finder and our Mobile Mechanics are proving increasingly valuable. 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. And where the problem is more complicated, the Mobile Mechanic and car owner can discuss the best options for getting the vehicle running again.

Edmund King, AA president, added:
“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. We have adapted our service to what people want, to save them time and to ensure their vehicle is ready for any journey, short or long.

“As the summer holidays draw to a close and the school run beckons, it makes sense to give the car a quick health check. 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.”