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.

[killcrap]

you probably have a diesel car right? i didnt think they had check engine lamps. but any who, the injectors clogging up is a poor diagnosis, adding anything to the fuel tank besides fuel and techron is a bad idea. get a BMW fault code read out, not a generic OBD2.

[Weasel]

"something about using an additive"? The check engine light will not set from using an additive, it is likely a fuel mixture type situation in the order of lean mixture or rich mixture at idle. Adaptive values to a BMW is the fuel trim at idle. If the fault was adaptive mixture too lean, it is caused by unmetered air in the form of a vacuum leak or torn intake boot.

And by the way, the OBDII reader will do nothing with the brake pads warning, after the pads and sensor are changed you simply need to turn the key on leaving engine off for about a minute and it resets during a system check.

[RJRDenver]

Not a diesel

Originally Posted by killcrap

you probably have a diesel car right? i didnt think they had check engine lamps. but any who, the injectors clogging up is a poor diagnosis, adding anything to the fuel tank besides fuel and techron is a bad idea. get a BMW fault code read out, not a generic OBD2.

[RJRDenver]

I'll get the most recent error code soon and start from there.

I didn't know the key in position 2 for a few seconds would reset the brake light. I was under the impression it had to be done from the OBD. But you're likely correct that simply putting the key in and setting it to the on position (2) without starting the vehilce allowed it to run its self test and clear the light, which is what we did when we plugged in the ODBII reader. Good to know.

Originally Posted by Weasel

"something about using an additive"? The check engine light will not set from using an additive, it is likely a fuel mixture type situation in the order of lean mixture or rich mixture at idle. Adaptive values to a BMW is the fuel trim at idle. If the fault was adaptive mixture too lean, it is caused by unmetered air in the form of a vacuum leak or torn intake boot.

And by the way, the OBDII reader will do nothing with the brake pads warning, after the pads and sensor are changed you simply need to turn the key on leaving engine off for about a minute and it resets during a system check.

[RJRDenver]

Ok, so I stopped by a local shop and used their ODBII reader and the following errors are reported. The device is a CanOBD2 device (www.canodb2.com) but you have to pay to get the details behind the codes. Any ideas based on the basic info given?

P2189 - System too lean at idle - bank 2

P0440 - Evaporative Emission System

Tomorrow is forecasted to be our last day of below freezing and it will start warming up here in Denver. As last time, I suspect the errors are going to clear when the temperatures increase.

Any ideas based on these two codes?

[RJRDenver]

I searched the first code (P2189) and found a couple threads on Xoutpost that were related. One in particular stands out:

Originally Posted by JonK

I had SES light turned on 2005 4.4i immediately after I performed an intermittent oil change. Engine oil level I checked with my dip stick was low after 8.5 quarts of oil so I put one more quart but it didn't fix the problem. I took my X5 to the dealer and my service adviser told me SES is only to do with exhaust system. After the technician checked the error code, my adviser asked if I have been very low on gas and I said "never."

Still they concluded that at certain point my gas was so low it messed up engine firing order. They had to reset it and it was good to go.

The interesting fact is during this period I was getting better gas mileage like +2MPG.

http://www.xoutpost.com/bmw-sav-foru...7-p2189-2.html

The interesting part is I know this last time I got gas, I was extremely low. Light on and remember thinking both times the car has never held as much gas. Wondering if letting the gas get so low really causes this problem. Don't usually let this happen, but two occasions have occurred recently.

[Weasel]

Originally Posted by RJRDenver

Ok, so I stopped by a local shop and used their ODBII reader and the following errors are reported. The device is a CanOBD2 device (www.canodb2.com) but you have to pay to get the details behind the codes. Any ideas based on the basic info given?

P2189 - System too lean at idle - bank 2

P0440 - Evaporative Emission System

Tomorrow is forecasted to be our last day of below freezing and it will start warming up here in Denver. As last time, I suspect the errors are going to clear when the temperatures increase.

Any ideas based on these two codes?

The system too lean at idle points to a vacuum leak, check the intake boot to the throttle body and idle motor for a tear if you have a 3.0i, vent hoses to the back of the manifold/valve covers if you have a V8.

The evaporative systems fault is the gas tank leakage emissions type thing, that is the fault you get if you leave the gas cap loose or fill up with it running etc. Check the cap first, if the fault keeps returning you will need to bring it in as it could be anything from a sticking vent valve to a bad DMTL pump.