March 23 2017 4 23pm.
Gas cap not sealing.
Generally gas caps can be used as a closure for the fuel tank.
Sometimes even new fuel caps have problems like this ac delco gt291 that locks too early.
Anyone with info please let me know.
On newer cars the emission control has an engine light which turns on when there is a leakage.
Their purpose is simple.
If the gas cap gasket is pinched dirty cracked or broken it can cause the gas cap to not seal properly and most likely will not click there are a few other parts but they don t impact the caps ability to secure onto the gas tank.
One of the tests is that they verify the gas cap is performing sealing properly.
These codes typically will be in the p0400 series and could indicate something more serious than a loose gas cap such as a broken seal or even a leak in the gas tank which is a much more serous problem.
A modern gas cap serves several functions.
If the parts above that will cause the gas cap to not click are damaged the gas cap will need to be replaced.
Then tighten the gas cap with your hand until you hear the cap click in place.
If the seal is damaged or the cap cannot properly seal the tank the lights will glow continuously.
Many cars will also generate a warning signal if the on board computer detects any fuel vapor escaping from the gas tank.
If you are satisfied that the gas cap is not damaged fully install it into the filler tube.
The most common cause of a lit check engine light is not a bad sensor it is a loose gas cap.
Today s fuel systems require a complete seal on the tank without it there can be issues.
The gas cap has air vents to allow the air to enter into the tank to maintain pressure.
If your gas cap is not properly attached you may see a check engine light or a loose cap warning light on the dash.
You can either tighten the cap and wait for the system to reset itself when it determines the problem is fixed or you can use an obd ii code scanner to manually reset the system.
It is a good idea to inspect the seal that is between the gas cap and the filler tube for any tears or cracking that could cause a vapor leak.
To prevent dirt debris and dust from entering the gas tank as well as providing a reliable seal.
What may surprise you is that many new vehicles are being designed without gas caps at all.