Motorists have discovered the true reason there is a flap in almost every petrol and diesel car in the UK with a wire located inside fixing a major fuel cap issue.

Road users rely on their fuel cap door from opening and closing to top-up their vehicles at the petrol station.

However, occasionally the flap could become stuck in place, preventing motorists from getting access to their tank.

The issue could cause a nightmare for road users desperate to top-up but a simple tip could prevent road users from being left hot and bothered.

According to TikTok users, the flap in their boot hides an important cable which can override the system and open the fuel cap door in seconds.

@pamtechgroup posted: “Sometimes your fuel tank cap won’t open. Most technicians will try to force it open with a screwdriver. It will only damage your paint. Don't do that. Do this instead.

“Open your trunks and reach for the side where your fuel tank is located. You will find a slim wire that is the fuel tank pull ring. Just pull it back slightly and your fuel tank cap will open.”

@andycharger said: “That’s no problem. Just open the boot. Locate this flap inside the boot wall. Open it up, get hold of this cable and now you can refuel your car.”

Experts at Ask The Mechanic also suggested that manually pulling the locking mechanism would solve the issue.

However, motorists who were unsure how to release the latch could open the cap with some more accessible options.

They explained: “Can't open fuel filler flap, first make sure central locking is working correctly, if ok try applying slight pressure to flap as you unlock the car.”

Specialists at Grimmer Motors claimed that a simple obstruction in the fuel cap door may be enough to solve any jams.

They added: “Inspect the fuel door area for any obstructions that might be preventing it from opening.

“Sometimes dirt, debris, or ice can accumulate around the fuel door, hindering its movement. If you notice any obstructions, carefully remove them and attempt to open the fuel door again.”

Grimmer Motors added that problems with the fuel door may have been caused by a range of simple reasons.

They stress most vehicles have a cable which runs from a fuel door lever to the fuel cap door. If this becomes loose or breaks it won’t open and will have to be replaced.

A faulty hinge or spring could also be behind the problem which will also have to be fixed by experts.

A blown fuse or damaged wiring where electricity is not reaching the door could also be the cause of the issue.