I have asked this before but did not get an answer so I try it again.

I would like to know how the systems detects the large leak.
What part is responsible for it or measure the pressure in the system.

I already change the Purge-valve, CCV, Hoses, O-Rings etc. but P0455 still appears from time to time. (often after entering a tunnel)

Thanks

 

There is a pressure sensor on the top of the fuel tank (on the EVAP FLANGE).

bob gauff

 

did you change the gas cap? that if all other suspects have been eliminated is usually the issue. use only OEM, to many issues with aftermarket, And the short stub hose between the CCV (cannister close valve) and charcoal can is another big issue.

 

Gas Cap was the first step, and the short hose leaked but is replaced (was my big hope).

Also the green O-Rings of Canisters (At Jaguar Dealer : 13.00 / At Ford Dealer: 3.50)


Its funny as I sometimes have no message "Check Gas Cap" for weeks and then it comes on very often. Most of the time when fuel tank is almost empty.

 

Where would you inject smoke to test this system so as to determine whether or not there is a leak?