Check engine light is confused.

kefler · 09-10-2008, 10:57 PM

About 10 days ago, the SES ("Service Engine Soon") light came on the instant I started the car after getting gas.. I was up in the mountains at about 5300ft. The car was driving fine so I drove it back home about 200 miles. iDrive says everything is Ok, nothing in any of the displays.

I called the dealer the next weekday and they said to check the gas cap, and made an appt for me to take it in.. They said to cancel if the light went off on it's own.

Well, after a week and a half, it's now about 2 days before my appointment and tonight the light went off. I've driven about 300 miles since it came on, and have filled up gas during that time as well. I have no idea why it went off now, but it seems like if it was a loose gas cap it would have gone off sooner?

Should I just pretend I never saw it and cancel the appointment?

Since people click on threads with pics in them, here is a picture of a squirrel I took in the mountains:

BK · 09-10-2008, 11:08 PM

I'd cancel the appointment if the light is off and the car is driving fine. The next regular appointment, they can check to see what codes were stored with the check engine light.

The car monitors the pressure in the gas tank. When it finds the system is not pressurized, it will throw the check engine light. After you put the cap back on, it requires some number of "successful" pressure checks before the car computer is satisfied nothing is wrong and turns the light back off. That's why it usually takes a few days for the light to go back off even after you fix the gas cap.

Staszek · 09-10-2008, 11:17 PM

Quote:

Originally Posted by BK

I'd cancel the appointment if the light is off and the car is driving fine. The next regular appointment, they can check to see what codes were stored with the check engine light.

The car monitors the pressure in the gas tank. When it finds the system is not pressurized, it will throw the check engine light. After you put the cap back on, it requires some number of "successful" pressure checks before the car computer is satisfied nothing is wrong and turns the light back off. That's why it usually takes a few days for the light to go back off even after you fix the gas cap.

What he said. It sometimes can take a long time for the light to go off after a gas cap related pressure loss occurs. Happened to a friends car (non BMW) and it took two weeks to reset.

kefler · 09-11-2008, 12:13 AM

Cool thanks! this makes me feel better.

I have more pictures of the squirrel plus some birds available upon request.

CALIF65GM · 09-11-2008, 10:20 PM

LOL this exact samething happened to me. My SES light was on for 2-weeks and 2-days before my appt. it went off.

I had an appt for something else, so had to take it in anyways.

Interesting my light came on in higher elevations too (Vegas). I drove about another 1000-miles before my appt.

It turned out to be the DMTL Pump. The computer stored 17-occurences of the fault.

I'd take it in if I were you and get it taken care of.

BTW has your car experienced any unusual rev surges while slowing to a stop?

kefler · 09-12-2008, 12:09 AM

ah dang I just cancelled the appointment today... then going out of the country for a bit. Well, I'm still not 100% sure that I tightened the gas cap properly just before it came on. I stopped right away and checked and I'm sure I had clicked it 3 times but it seemed to click a few more times easily, so I don't know if I didn't do it right.

It's good to hear it took about a similar amount of time for your light to go off.

As for surging, I don't think I have anything like that.. The car makes some odd sounds sometimes, in the heat of the summer the AC will sound REALLY loud occasionally...

voltron1011 · 09-12-2008, 03:14 PM

Mazda actually has a 'check fuel cap' icon-light for some of their cars, just for situations like this...

3pnt4maro · 09-12-2008, 08:08 PM

I learned a trick of the trade after suffeirng from this quite a few times when I first got this car...if you read carefully in the owners manual it says that when the fuel pump clicks off for the first time stop right then and dont try to round your price up....ie: if it clicks at 53.26.....then dont try and round up to 53.50 or 54.00 etc...pull it out right then...the manual indicated that when the pump shuts off that the tank is completely full and still has the proper allowance of air in the tank to get the proper pressure readings....try it...I havent had any problems since

09-10-2008, 10:57 PM	#1
kefler Lieutenant 123 Rep 420 Posts Drives: 2018 X5m / Alpine White Join Date: Jan 2008 Location: Arizona iTrader: (0)	Check engine light is confused. About 10 days ago, the SES ("Service Engine Soon") light came on the instant I started the car after getting gas.. I was up in the mountains at about 5300ft. The car was driving fine so I drove it back home about 200 miles. iDrive says everything is Ok, nothing in any of the displays. I called the dealer the next weekday and they said to check the gas cap, and made an appt for me to take it in.. They said to cancel if the light went off on it's own. Well, after a week and a half, it's now about 2 days before my appointment and tonight the light went off. I've driven about 300 miles since it came on, and have filled up gas during that time as well. I have no idea why it went off now, but it seems like if it was a loose gas cap it would have gone off sooner? Should I just pretend I never saw it and cancel the appointment? Since people click on threads with pics in them, here is a picture of a squirrel I took in the mountains: Attached Images
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09-10-2008, 11:08 PM	#2
BK Smiling politely 165 Rep 7,931 Posts Drives: 330i Join Date: Feb 2006 Location: Washington DC iTrader: (0) Garage List 2006 330i [9.00]	I'd cancel the appointment if the light is off and the car is driving fine. The next regular appointment, they can check to see what codes were stored with the check engine light. The car monitors the pressure in the gas tank. When it finds the system is not pressurized, it will throw the check engine light. After you put the cap back on, it requires some number of "successful" pressure checks before the car computer is satisfied nothing is wrong and turns the light back off. That's why it usually takes a few days for the light to go back off even after you fix the gas cap. __________________ E90 330i Black Sapphire 6MT \| 991.1 C4 Platinum Silver 7MT
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09-11-2008, 12:13 AM	#4
kefler Lieutenant 123 Rep 420 Posts Drives: 2018 X5m / Alpine White Join Date: Jan 2008 Location: Arizona iTrader: (0)	Cool thanks! this makes me feel better. I have more pictures of the squirrel plus some birds available upon request.
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09-11-2008, 10:20 PM	#5
CALIF65GM Colonel 97 Rep 2,041 Posts Drives: e93-35 May08 ED Join Date: Jun 2005 Location: SF, CA iTrader: (0) Garage List 06 - Oct. 05 build ... [0.00]	LOL this exact samething happened to me. My SES light was on for 2-weeks and 2-days before my appt. it went off. I had an appt for something else, so had to take it in anyways. Interesting my light came on in higher elevations too (Vegas). I drove about another 1000-miles before my appt. It turned out to be the DMTL Pump. The computer stored 17-occurences of the fault. I'd take it in if I were you and get it taken care of. BTW has your car experienced any unusual rev surges while slowing to a stop? __________________ 5-2-08 e93-35 ED Montego w/Jade Grey, Step w/Paddles, PP, SP, CA, hot seats and iPod.Awaing re-delivery soon. Debadged 330xi ED 11/14/05 Auto/Mystic Blue/Gray leather with Alum/PP/SP/CA/Fold-down rear seats/Alarm. Sold to Carmax on 6/7/08 with 50,624 miles on clock
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09-12-2008, 12:09 AM	#6
kefler Lieutenant 123 Rep 420 Posts Drives: 2018 X5m / Alpine White Join Date: Jan 2008 Location: Arizona iTrader: (0)	ah dang I just cancelled the appointment today... then going out of the country for a bit. Well, I'm still not 100% sure that I tightened the gas cap properly just before it came on. I stopped right away and checked and I'm sure I had clicked it 3 times but it seemed to click a few more times easily, so I don't know if I didn't do it right. It's good to hear it took about a similar amount of time for your light to go off. As for surging, I don't think I have anything like that.. The car makes some odd sounds sometimes, in the heat of the summer the AC will sound REALLY loud occasionally...
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09-12-2008, 03:14 PM	#7
voltron1011 Colonel 119 Rep 2,909 Posts Drives: 2011 135i, FJR-1300 Join Date: Apr 2005 Location: Wiesbaden iTrader: (2)	Mazda actually has a 'check fuel cap' icon-light for some of their cars, just for situations like this... __________________ '06 E90 325i (Delivered May '05) 6-spd manual, Nav, Xenons, 18' 162's, sport-suspension, 15mm RE spacers, NURBURGRING: http://www.e90post.com/forums/album.php?albumid=3270
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09-12-2008, 08:08 PM	#8
3pnt4maro Long Time Lurker 22 Rep 352 Posts Drives: 2006 BMW 330I Join Date: Aug 2008 Location: LaGrange, Georgia iTrader: (0)	I learned a trick of the trade after suffeirng from this quite a few times when I first got this car...if you read carefully in the owners manual it says that when the fuel pump clicks off for the first time stop right then and dont try to round your price up....ie: if it clicks at 53.26.....then dont try and round up to 53.50 or 54.00 etc...pull it out right then...the manual indicated that when the pump shuts off that the tank is completely full and still has the proper allowance of air in the tank to get the proper pressure readings....try it...I havent had any problems since __________________ 2006 BMW 330i-E90-14.4@96mph-Daily Driver BSM, Premium Package, Logic 7, BMS Powerbox, 19 VMR Wheels Staggered (19x9 and 19x10), 20%Tint, LED Lights, 2 Rockford Fosgate Punch P2 10's with amp in a custom setup.
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