Service Engine Soon Light on

[RJRDenver]

Sorry for the length of this post...

So for the second time, we've had some pretty cold weather here in Denver this year and I've had similar issues each time the weather has gotten drastically cold.

The first time, about a month and a half or so ago, I happened to stop and get gas on my way home to ensure I had a full tank in preparation for a significant amount of snow fall expected.

The next morning upon starting the vehicle, my "Service Engine Soon" light illuminated. It was extremely cold and I figured that it might be related to temperature and or that I didn't tighten my gas cap the night before. I checked the gas cap and it was secure. I removed and reseated it just to be sure, but the Service Engine Light remained illuminated for a couple of days, all the while, we had very cold temperatures. I read in the manual that the Service Engine light is related to emissions and that it is not as critical of an issue unless flashing (which indicates sever mis-fires). Anyhow, I decided to wait it out until we got temperatures that were above freezing and low and behold, the light went off without changing anything other than temperature outside. I was still slightly confused and perplexed why temp. could affect the vehicle but I assumed maybe I got bad gas or something that night before the storm blew in.

Shortly after the weather cleared up, I did my rear brakes and had to go to my local auto parts store to use the ODBII reader to clear my brake warning light indicating I needed to service my brakes. Upon hooking up the ODBII reader, the device read older messages which included a code (Don't remember exact code any longer) but it mentioned adding a fuel additive, which made me further believe I may have gotten some crappy gas, which set off the Service Engine light / emissions warning system.

Well, now the second coldest snap of weather has set in over Denver and the Service Engine light has come back on. Coincidentally, it happened the day after getting gas again. Right now, those are the two common elements of the problem. Weather temps cold, below freezing and pumping gas during this cold period. I haven't gone to the auto parts store to read the code again, but I'm suspecting something similar as last time.

The guy at the parts store thinks maybe my injectors are gunked up and as a result the emissions system is measuring poor performance when cold. Ok, I buy it. He suggests running something through the fuel to clean the fuel system. He didn't suggest any particular product, instead, he said to call and ask BMW because he wasn't familiar with a known good product to try in the car - which I appreciated. He was honest and didn't trust himself to advise me on putting something in the gas tank, but he did say, check out seafoam or something like that. Any suggestions, experiences, etc?

Also thinking maybe I could try replacing the gas cap since it has been a common element of the issue occurring, although, I've gotten gas while it was warm out in between these two occurrences and didn't have the problem which leads me back to more of a temperature related issue.

Any feedback would be appreciated.