UK drivers are being warned that common winter car faults could leave them facing repair bills running into the thousands, with new data suggesting a single cold snap can be enough to deliver a serious hit to household finances.
The warning comes from automotive diagnostics specialist Carly, which analysed more than 2.4 million vehicle diagnostic sessions carried out between October and December 2025.
Its findings show that the most common cold weather faults could cost drivers as much as £2,481 to fix, a figure equivalent to around two months’ rent for the average UK household.
According to the data, winter breakdowns most frequently stem from glow plug failures, auxiliary coolant pump faults, and malfunctioning air quality sensors, all of which tend to strike during colder months when vehicles are under greater strain.
Glow plug failures, which affect diesel vehicles only, were found to account for around 60% of winter fault codes, with the most expensive repairs linked to defective control units costing between £848 and £1,266.
Other glow plug related issues included defective plugs costing up to £835, along with wiring or fuse problems that, while cheaper, can still add to unexpected bills.
Auxiliary coolant pump failures were also common, appearing in 65% of winter fault cases, with pump replacement costs typically ranging from £570 to £820.
Faulty air quality sensors were the most frequently logged issue overall, appearing in 78% of cases, with repair costs varying from £281 to £395 depending on the cause.
Carly said these faults often emerge at the worst possible time, during peak winter travel and holiday periods when household budgets are already under pressure.
Commenting on the findings, Dali Ati said winter breakdowns remain a major and costly issue for UK motorists.
“Our data shows that some of the most common faults reported during colder months can also be among the most expensive to fix.
“This is particularly challenging for owners of diesel cars, where glow plug failures are both likely and costly.”
He said greater awareness of vehicle health could help drivers avoid being caught out.
“With better visibility of vehicle health, drivers can prepare more effectively and avoid unexpected repair bills.”
Carly said understanding which faults are most likely to occur during winter allows drivers to take preventative action and reduce the risk of breakdowns during the busiest times of the year.
The company offers a plug in diagnostic system that connects to a vehicle’s OBD port and provides drivers with professional grade insights into potential issues.
Carly’s diagnostic tool is available in Basic and Premium packages, with prices starting from around £40.
View more about what Carly’s OBD solution can help drivers with here
