I also posted this in the Seville forum, not sure where the best place to get an answer is...
I own a 2000 SLS with 100,000 miles, and yesterday I was sitting at a drive through window and the car stalled. I restarted it, and the "Service Engine Soon" light came on and stayed on during my 20 mile drive home, but the car drove normally. When I got home I read up on how to enter diagnostic mode, and the displayscrolled quicklythrough every code option, some saying no codes, and a few saying code ##### history (unfortunately I wasfoolish and didn't write them down). The display then went to "Clear all codes?", at which point I switched the ignition off, figuring that the code histories would be saved. I took it into a service shop this morning for an engine diagnostic, and I noticed the "Service Engine Soon" light was no longer illuminated. The service shop just called me to tell me that they couldn't find any codes. I havetwo questions:
1. Could I have cleared the code histories and "Service Engine Soon" lightby turning the ignition off in diagnostic mode?
2. Will the codes come back if it is a reoccurring problem?

At this point I'm just having the shop perform the recommended 100,000 mile maintenance, but I'm worried that something is wrong. Any help is greatly appreciated!

 

Yes

 

Just want to point out that the check engine lights exist because of government regulations on emmissions. Manufacturers chose to name them Service Soon or Check Engine. Those names terrify people and get them worried that some terrible thing happend to their motor. Fact is it is 99.9% of the time related to fuel air and spark. I am not saying do not investigate it but don't get overly worried. There is another thread here and yours truly and slowroll who answered here mention that loose gas caps cause the lights to come on, so something that minor can be the culprit. Bad spark plugs, bad oxygen sensors too but don't for one minute think your engine needs an overhaul because the light came on.

 

Thanks for the replies. The shop put in new spark plugs, checked the fuel pump, and gave the car a tune-up. I picked up the car today, droveabout 10 miles home, and as I wasturningthe cornerinto my neighborhood at about10-15 mph the car stalled again. The only light illuminated on the dash was the battery light. I pulled the car to the curb, put it in park, and then started it. It started up right away, didn't display any warning lights, and drove fine for two blocks to my house. I checked the display, and the battery voltage was fine. Any thoughts? I'm taking it back to the shop tomorrow, but it would be nice to point them in the right direction...

 

Its a guess, but I suspect it may be crank sensors. Codes may be stored even though light is out.