What is a fuel filler cap?
The fuel cap, also called the fuel filler cap or gas cap, is a small plastic or metal part that sits at the top of the gas tank and secures its entry. It’s designed to seal a vehicle's fuel tank to prevent fuel from evaporating or spilling out and keep contaminants, such as dirt and dust, out of the fuel tank. All of this helps to maintain the integrity of the fuel system and prevent engine damage. A tight seal on the gas cap also ensures the fuel tank can pressurize properly.
Depending on your vehicle's make and model, your fuel cap may have a locking mechanism, which requires a key or combination to open.
How do I know if my fuel filler cap needs replacing?
If you don’t notice any physical damage to your fuel filler cap, there are some common symptoms to keep an eye out that suggest it might need replacing:
Cap is not tightening properly
Check engine light illuminates
Threads on the cap are stripped
Gasket of the cap is split or missing
Inspecting your fuel filler cap regularly can help catch issues before they arise.
How often should you change your fuel filler cap?
Good news for drivers looking to save money on car expenses
—you don’t have to change your fuel filler cap unless there’s a problem (it’s damaged or stolen). While there’s no set interval for replacing your fuel filler cap, some mechanics suggest that the gap cap will last up to 50,000 miles before needing a replacement to prevent wearing and maintain a tight seal. But if properly cared for, it could last longer.
When servicing your car, ask your mechanic to inspect your fuel filler cap to ensure no damage.
Can I replace the fuel filler cap myself?
If you want to cut your car repair costs, consider changing your fuel filler cap at home. With a few simple tools, the replacement is easy. But if you’re not comfortable performing the replacement, call your local mechanic and leave the job to a professional.