I have a '99 and it has been contiually throwing a code 0455 "Evaporative Emission Control System Leak Detected(Gross Leak). I have gone over it myself and had a mechanic look it over and put it on a smoke machine but can find no leak. Oddly, its seems I can replace the gas cap and it will fool the system long enough to get it inspected. Any ideas are appreciated. Any experiences with the same? I am tired of buying gas caps. It is either that or when reset the OBD computer it will not throw the code for a short period of time. I go thru this to get it inspected every year and it lasts about 200 miles before the check engine light comes back on. I missed getting it inspected this time because I haven't had time to fool with it. Thanks in advance.
Doug

 

The fuel cap is the easiest fix. But it can be other leaks. Pages from Bosch manual that show how this is calculated and what other factors are going on is attached. Once cleared, the code can won't re-appear for two drive cycles.

 

With a gross leak, it should be pretty easy to find with a smoke machine. Find a new mechanic. Its eithet a charcoal canister, the cap or the purge valve.

 

Thank you for the replies. So let me see if I understand the Evaporative Emission System monitoring PDF Savannah sent me.
It mentions as "secondary parameters" that things like purge vapor factor, fuel tank pressure, battery voltage, fuel tank level, among others, may also affect it?
Also, it takes two drive cycles to reset that particular code, so if I make the fix and time my inspection to fall between the first and second drive cycle I should be able to pass. What someone needs to come up with is a computer program or chip to bypass all of this code stuff in the computer
What I can't seem to wrap my head around is what can go wrong with a gas cap in a couple of months?????
By the way, where is the purge valve located?