P0442 and p0456

2004 Kia amanti. P0442 is pending always and p0456 just illuminated my light

I sprayed the engine bay and don’t here change in idle . Also the gas cap looks fine. What else is next?

Remove the gas cap, and apply a small amount of petroleum jelly to the seal on the gas cap and reinstall the gas cap.

If the CEL turns off, replace the gas cap.


@Tester the seal would be the rubber ring correct?



@Tester I don’t have any jelly. Would dielectric grease work? Or I heard even oil works


Don’t use dielectric grease. It contains silicone.

Use a petroleum oil then.


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@Tester ok so 5w 30 won’t work? If not I’ll just pick up some pet jelly

I don’t know of a single mechanic that doesn’t have a jar of pet jelly on hand.

It’s used for many ways in automotive repair.


Here in San Jose our cars have to pass emissions testing every two years. Part of the test is the gas cap seal. They remove the gas cap and screw it onto a test fixture that somehow tests if the seal is good or not. After failing that test once — which involves a big hassle — since then before taking the car in for testing I always clean the gas cap o-ring, then rub a little engine oil on it. Passed that test every single time since.

So engine oil does work haha ! I’ll try this then @George_San_Jose1