My 2017 f type s had a gas cap issue - leak causing check engine and restricted performance….. cap replaced by jaguar . Now 2 months later I’m having the same issue with check engine due to leak. What could be going on? Could the actual tank where cap screws into have an issue? Thanks

 

Yeah, totally get it. So if a brand new cap didn't fix it, the problem is likely somewhere else in that system. The most common thing on these cars is the actual plastic filler pipe where you screw the cap on it can crack or warp. Also, sometimes a small hose underneath gets knocked loose or dry rotted. Might be worth having them check those spots instead of just throwing another cap on it.

 

First, get a DTC code. Could be a different component of the Evaporative system.



Verify that there is no damage to the filler neck where it contacts the gas cap's gasket.

A little ding can cause the issue.

A light coating of petroleum-resistant grease ("brake grease') on the gasket of the cap will help reduce issues.

 

Thanks!

 

The original cap on my 2017 took 2-3 clicks to lock completely. The new cap I have doesn't do that, but you do have to press in and rotate as much as you can. A failure to close it completely will create that CEL. Have the same issue on my 2013 Golf.