The most common cause of a lit check engine light is not a bad sensor it is a loose gas cap.
Gas cap not sealing.
Today s fuel systems require a complete seal on the tank without it there can be issues.
If your gas cap is not properly attached you may see a check engine light or a loose cap warning light on the dash.
Their purpose is simple.
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.
The gas cap also known as the fuel filler cap is a simple but important component that is found on the vast majority of road going cars and trucks.
If the parts above that will cause the gas cap to not click are damaged the gas cap will need to be replaced.
On newer cars the emission control has an engine light which turns on when there is a leakage.
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.
One of the tests is that they verify the gas cap is performing sealing properly.
What may surprise you is that many new vehicles are being designed without gas caps at all.
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.
I can t find anything on the e check website for how they handle when a manufacturer makes a car without a gas cap.
Generally gas caps can be used as a closure for the fuel tank.
To prevent dirt debris and dust from entering the gas tank as well as providing a reliable seal.
Sometimes even new fuel caps have problems like this ac delco gt291 that locks too early.
If the seal is damaged or the cap cannot properly seal the tank the lights will glow continuously.
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.
Anyone with info please let me know.
Steve from cars simplified takes a look at this fuel cap on a 2005.
Many cars will also generate a warning signal if the on board computer detects any fuel vapor escaping from the gas tank.
March 23 2017 4 23pm.
If you are satisfied that the gas cap is not damaged fully install it into the filler tube.
