bcdanzig

I have a 2004 E320. I just started getting the red check fuel cap error and the check engine light has come on. After scanning for the code errors the first and only code error was P0451 EVAP large leak error. I replaced the gas cap with a Stant cap and cleared out the code. About 2 weeks later, I received the red check fuel cap error and the check engine light came on again. I scanned the codes and receive code errors P0451 again along with P0455. I checked the cap and cleared the codes. A couple of days later, the same errors came back. I have noticed that each time it was after filling the tank driving for about 45 miles and then sitting idle at a long stop light. After the tank gets to about 1/2, I never have an issue.

Looking for a solution, since I am baffled!

1badSLS

evap leaks are a PAIN IN THE ... fuel filler necks, purge valves, charcoal canisters all known to cause this problem, the dealer will likely have to smoke test the vehicle to determine what component is actually leaking

bcdanzig

I am going to check the hoses to the evap valve as soon as the weather gets a little warmer. It is just weird that the only time I get the error is when the fuel is over the half tank mark. Once it goes under a half a tank, I never have a problem. And the error only happens when I come to a stop for a period of time after driving for about 30-45 minutes.


Sorry I didn't get back to you sooner. Had some health issues that kept me off this site.