I have been hunting this code down for over a month now and have not been able to figure it out. I read on a BMW site, it was due to a leak with the air charge pipe. I have an aftermarket silicone air charge pipe and don't think that is causing a leak. This past weekend I checked all of the intercooler clamps and everything was tight. I am currently running the HFS-4 with a tune on my N18 in addition to an aftermarket intercooler, downpipe and a bunch of other mods. Has anyone had any experience with this code. I have searched and found zero results. I have attached a photo of the specs from the program I am using to read the codes. Any help would be greatly appreciated. PS - The interesting part is when the CEL is triggered I am always cruising on the highway and when I go to accelerate to pass someone, that's when the light is always triggered. No other time.