Pointers for P0455?

[dizman7]

I've been getting this on and off for the last month or so, some times weeks in-between other times the next day. I replaced the gas cap with a cheap $5 Autozone one and I still get the code. Though I'm sure it doesn't matter but should I maybe try an actual new BMW one instead first?

Researching this I noticed no one mentioned this, so I thought I'd put it here and see if it's might narrow down where to look. EVERY time I have got this error code I have been at a stop light for a good 30secs or more with my foot on the brake then the engine randomly drops in rpms below idle for a sec, which the CEL then comes up. It's usually after I've been driving for 15mins or so too.

I know there are few different places to start looking, not sure if this helps at all to narrow it down a bit.

Thanks

[Mileage]

Bumping this thread. I have the same exact symptoms. Was at a stoplight for a good minute. Heard a faint click from the rear, my idle dipped briefly, and the CEL came on. Autozone reader said it as P0455. I already looked at the gas cap since that is the first place to start. Gas cap looks fine around the seal. Car runs strong other than that. Any ideas where I should be poking my nose?

[marvinstockman]

The car is 18 years old, and you need to check all the vacuum hoses that are part of the emissions control system. On my 2003 Chrysler van, it was a cracked hose on the charcoal cannister.