Some used cars risk being written off if lights are damaged.

The cost of replacing a broken headlight can be so great that some second-hand cars with damaged lights risk being written off, according to new research.

A study into 13 popular cars by consumer website WhatCar? found that a blown headlight bulb could cost as much as £846 to replace.

However, the cost was considerably reduced for vehicles without HID or LED bulbs. For example, a standard VW Polo comes with traditional halogen bulbs, which cost owners just £18, but the high-spec Polo GTI model comes with sealed LED headlight units, which cost more than £800 to replace.

Volkswagen headlight

Similarly, Suzuki Swift SZ3 or SZT owners will have to shell out a mere £4 to buy a new bulb, but those with a more luxurious SZ5 model will have to pay £684 for a replacement HID unit.

And even in cases where the HID or LED lights aren’t housed in sealed units, the research found that bulbs are still more expensive to replace than normal halogen bulbs.

Audi Q7 Matrix Headlights

The HID bulb for a Vauxhall Corsa Elite, for example, costs £317, while a halogen bulb for a more modest Corsa costs £17. It’s the same story for an Audi A1, which features £18 halogen lights on the SE trim, but S-Line Nav models would cost their owners £211 for a new HID bulb and control unit.

Claire Evans, consumer editor at What Car?, said HID and LED bulbs would last longer than normal halogen bulbs, but that those buying used cars with more powerful lights would find repair bills tough to stomach.

Vauxhall Corsa Griffin

“The longevity of HID bulbs makes them a viable option on a new car,” she said. “However, if you are buying a used car as a second household vehicle or as a first car for a son or daughter, you – and they – could be landed with a massive repair bill for a blown bulb that could even render the car a write-off due to it being uneconomical to repair.”

Greg Whitaker, editor of What Car?’s sister title Car and Accessory Trader said he expected the cost replacement of headlight units to fall in future as the aftermarket sector catches up with the manufacturers in headlight technology.

Private Car Park

“It’s happened in the past with a number of car parts,” he argued. “The floating speedometer needle in the Mercedes C-Class was prone to breaking and AC Tronics created a fix for this. And the ECU in the Vauxhall Meriva had some fragile components that frequently broke, so a fix for this was also created.”