4 Important Reasons to Replace a Missing Gas Cap


Although today’s passenger vehicles have a strip of plastic attaching the gas cap to the fuel filler inlet, that piece of plastic can eventually break. Now the owner must always remember to put the cap back on after refueling. If the cap does get lost, the owner may wonder whether replacing it actually is necessary. A small door covers the inlet, after all. Nevertheless, there are a few important reasons to replace a gas cap that gets lost.

The Risk of Dirt in the Tank

Even with the inlet panel door closed, dust can get into that hole and eventually be pushed into the inlet by the gas pump nozzle. This is especially a risk if the driver routinely travels on gravel or dirt roads. It’s easy to see just how much dirt can get into a car or pickup truck if the driver leaves the vents open or the windows down.

The fuel filter blocks most sediment from reaching the engine. However, in this situation, that filter may become clogged earlier than it otherwise would. The main symptom of a clogged fuel filter is reduced power during acceleration. The engine also may randomly misfire, a symptom commonly called ‘missing.’

Check Engine Light

One of the more disconcerting occurrences connected with a missing gas cap is the ‘check engine light’ coming on because of the extra oxygen in the fuel. The only way the driver can be certain the gas cap is the problem is to have a diagnostic check run on the system.

Air Pollution

Without a cap, fumes leak from the reservoir because the door is not a tight fit. This happens even though a spring-loaded flapper is in place that moves when a pump nozzle is inserted. These fumes are a source of air pollution, something that should be troubling to anyone who cares about the environment.

Fuel Evaporation

A small amount of gas continually evaporates without a tightly fitting cap over the inlet. This will not be a huge amount, but it still cuts fuel efficiency to a certain extent. 

Reasons to Buy a New Cap Instead of a Used One

A used gas cap can be purchased at a very cheap price, but it’s better to buy a new one from an auto parts store. Caps may not be available from the same vehicle model and year. Others will not fit perfectly. In addition, a used device from the same model and year will probably no longer fit tightly if the vehicle is old. Used caps pose the same problems as continuing without one, especially the likelihood of the check engine light turning on. New products are not as cheap as used ones, but gas caps are affordable to replace.

Concluding Thoughts

With four important reasons to replace a gas cap instead of continuing without one, vehicle owners understand why they should not delay making this purchase. Buying a new device instead of a used one is recommended. It’s a reasonably priced option that prevents the same problems associated with leaving the fuel filler inlet open.