If your gas cap won’t come off, you may not be able to refuel your vehicle, which can leave you stranded once the tank is empty. The issue may be caused by a stuck, cross-threaded, or damaged cap, or a problem with the fuel filler neck. An assessment will identify the cause and restore normal operation.

What does it mean if the gas cap won’t come off?

This usually indicates that the threads or locking mechanism on the gas cap are damaged, seized, or misaligned. In some cases, corrosion or dirt around the filler neck may also prevent the cap from loosening.

Common causes of a gas cap not coming off

• Cross-threaded or overtightened cap
• Damaged locking mechanism in the cap
• Corrosion or dirt buildup on the filler neck
• Broken or misaligned gas cap threads
• Locking gas cap key mechanism failure

Why do you need to fix this problem quickly?

If you can’t remove the gas cap, you won’t be able to refuel your vehicle once the tank runs low. Forcing it off may damage the filler neck, leading to more expensive repairs. Proper diagnosis is the safest way to fix the issue.

How do you know when to get it checked?

You should book an inspection if:

• The gas cap won’t loosen even when turned fully
• The cap spins freely without releasing
• You notice rust, dirt, or debris around the filler neck
• You have a locking cap and the key won’t turn
• The cap feels stuck or cross-threaded after refuelling

What happens during an assessment?

A mechanic will:

1. Inspect the gas cap for thread damage or locking issues
2. Check the filler neck for corrosion, dirt, or misalignment
3. Use specialised tools to safely remove a stuck cap
4. Replace the gas cap if damaged
5. Advise replacement of the filler neck if it is causing the problem

How much does it cost to fix?

Gas cap replacement typically costs $50–$120. If the filler neck is damaged and requires replacement, costs may rise to $250–$600+ depending on the vehicle.

Is it unsafe to drive with a gas cap that won’t come off?

It’s not unsafe in the immediate sense, but it will prevent you from refuelling once the tank is empty. Forcing the cap off can cause further damage, so it’s best to have it professionally inspected and repaired.