Hoses on charcoal canister and/or expansion tank.
Could also be (but is easy enough to check) the fuel cap is loose. If so, tighten, and the light should re-set itself.
Since you have the tool, check the cap, re-set the lights, and see if the same code pops up again.
Seems like I am doing a bunch for my ti lately. After repairing the Secondary Air Pump last weekend, I had another engine code pop up. P0455. I suspect it may be because I used silicone vacuum hoses, not the more rigid OEM vacuum hoses as original. I bet they are collapsing under vacuum load. I recall one of the longer ones was going under where the fuel filter is located and perhaps that's a contributing factor. .
If anyone has anymore recent experiences with P0455 codes, I'd like to read about them. Not very much about the codes on multiple forums.
Last edited by BlackBMWs; 04-09-2014 at 06:15 AM.
Charcoal canister is by the fuel filer behind the rear seat side panel.
Thanks J!m! I assume access is under the car like you'd access the fuel filter or by the rear wheel well. I see there are references to purge and vent valves being defective. I'll seek to locate those as well.
Last edited by BlackBMWs; 04-09-2014 at 03:59 PM.
I know this old but I just wanted to share with the code 455 of my 1998 318ti. I found a broken breather line at the left side tank, see the attachment with the arrow pointed and encircled. Troubleshoot; I plugged up both side but I cannot recommend this will be permanent fix until I can get the part. I will try to contact BMW but I doubt if they sell only that part instead they could sell me the tank itself. You need the breather tube to pass air from the other side of the tank. So far after resetting the failure code (455), it haven't trigger yet. I am planning to drill out the broken connector of the tank (plastic) then I replace with plastic fitting and bond with glue then connect to the hose. There are some glue that hold at least 90 PSI and can handle fuel and oil. I will up-date you guys if this thing works.
On my 99' it ended up being the fuel tank breather valve next to the secondary air pump in the engine bay. It was stuck closed, not allowing the pressure of the system to escape after it ran the test. Shot it full of brake cleaner and it started working like it is suppose to.
Super old thread, buti just started having a strange issue with my fuel breather valve. If i have the electrical connection plugged in the car runs really bad. On throttle it wont move at all. If i have it unplugged it runs fine. Any problem running with it unplugged?