Close

Gas Cap Replacement Cost

Know what price you should pay to get your vehicle fixed.

The average cost for a gas cap replacement is between $55 and $66. Labor costs are estimated between $17 and $23 while parts are priced between $38 and $43. Estimate does not include taxes and fees.

Find a RepairPal Certified Shop

Find a high quality auto repair shop or dealer near you
x

What is a Fuel Tank Filler Cap?

Modern vehicles with combustion engines are required to have a system in place that contains evaporation of fuel from the fuel tank, and recycles that fuel for use in the engine. This is because evaporation of gasoline and diesel is much more harmful to the environment than burning diesel or gasoline. In order to seal the inlet of the fuel tank, the fuel tank filler cap is used, and forms a true seal between the fuel tank filler neck and the operating environment. It is located behind the fuel filler door, and in nearly all states the driver of the vehicle takes it off and replaces it hundreds of times throughout the life of the vehicle.

How do Fuel Tank Filler Caps work?

To prevent the evaporation of fuel, the fuel system must be completely sealed from leakage, and the evaporated fuel must be contained for the engine to use at a later time. This poses one problem, how do you get fuel into the fuel tank. While fueling, evaporative emissions will leak out of the fuel filler neck, and many states have adapted to evaporative emissions systems installed on the fuel pump to curb this. When the fuel tank filler cap is reinstalled, however, the fuel system is sealed against evaporation due to a tight connection between an o-ring on the fuel filler cap and the fuel filler neck. This o-ring can hold pressures from the fuel tank, and overpressure is prevented by purge valves, vent valves, and fresh air valves. Some of these fuel tank filler caps are internal to the fuel tank filler neck, and require only the fuel pump to be inserted and removed to open and close the system.

What are the symptoms of a bad Fuel Tank Filler Cap?

For most vehicles, the only symptom will be a check engine light or fuel tank filler cap light illuminating on the driver instrument cluster. This is to signal that there is an evaporative emissions (EVAP) leak. In some situations, the vehicle may take longer than normal to start, or, more rarely, the engine may not start at all. on-board diagnostic (OBD) trouble codes will refer to EVAP system failures such as a small or massive EVAP system leak. Lastly, the powertrain control module may notice a lean running condition, which could even lead to random and infrequent misfires.

Can I drive with a bad Fuel Tank Filler Cap?

Changing the gas cap immediately is necessary to protect the environment and your vehicle from degradation. Not only are evaporative emissions more harmful to the environment than burning that fuel, but if the vehicle begins running lean it could cause excessive heat soaking of the engine, especially those directly involved in the combustion cycle. Also, if the lean operating conditions are recognized, the fuel economy of the vehicle may suffer as the powertrain control module attempts to compensate for the over-abundance of air by adding more fuel for each combustion event.

How often do Fuel Tank Filler Caps need replacement?

Fuel tank filler caps go bad quite often, and many times are replaced due to regular maintenance. Even if the fuel tank filler cap is not replaced, the o-ring which seals the cap to the fuel tank filler neck may be replaced instead. Anticipating more than 100,000 miles from one fuel tank filler cap is not likely realistic. Even if the fuel tank filler cap is not leaking enough to cause an OBD trouble code to be stored in the PCM, the cap will still require replacement if it tests poorly during scheduled maintenance. In order to keep the fuel cap and seal working longer, ensuring the cap and filler neck are clean when refueling.

How are Fuel Tank Filler Cap issues diagnosed?

Diagnosing a fuel cap would happen during scheduled maintenance for many makes and models of vehicles, or any time there is a detected EVAP leak or lean fuel to air ratio. In both cases, they will be visually inspected for degradation, cleanliness, and presence. Afterwards, if it looks to be in good operating condition, a pressure test with a fuel cap pressure tester will determine if it has failed.

How are Fuel Tank Filler Caps replaced?

Fuel tank filler caps go bad quite often, and many times are replaced due to regular maintenance. Even if the fuel tank filler cap is not replaced, the o-ring which seals the cap to the fuel tank filler neck may be replaced instead. Anticipating more than 100,000 miles from one fuel tank filler cap is not likely realistic. Even if the fuel tank filler cap is not leaking enough to cause an OBD trouble code to be stored in the PCM, the cap will still require replacement if it tests poorly during scheduled maintenance. In order to keep the fuel cap and seal working longer, ensuring the cap and filler neck are clean when refueling.

RepairPal Recommendations for Fuel Tank Filler Cap issues

Using aftermarket fuel tank filler caps is ok in most instances, however some vehicles will need to be replaced with a new cap from the dealership. We recommend doing due diligence to identify of a specific fuel tank filler cap is applicable to your make and model, as a poor match between the ca and filler neck will lead to a fuel cap that works properly, but cannot seal the fuel system.

What to look out for when dealing with Fuel Tank Filler Cap issues

Vented fuel caps are available, but will cause any modern vehicle to function incorrectly. sing a filler cap meant for an older vehicle will likely result in improper fitment, and will result in the symptoms noted. These caps are mainly for carbureted engines and marine applications.

Can I replace the Fuel Tank Filler Cap myself?

Replacing a fuel cap is as easy as fueling your vehicle, and much faster. Be advised that testing a fuel cap requires a fuel cap pressure tester, otherwise there is no accurate way to determine if it is functioning properly. If you do not have a fuel tank filler cap test kit, it is likely less expensive to have it tested and replaced, though replacement is the easiest repair that can be done to any vehicle.

19,509 people trusted RepairPal with their estimates this week!