P0171 P0174
 

Good evening X5'rs. I traveled from south carolina to dayton ohio for thanksgiving to see family. trip was fine the whole way. After being here a day my SES light came on. Local Advance Auto checked and gave me P0171 and P0174 codes. I have searched the forums and found a lot of info but my X is running fine. Mileage is good. I got 23-24 driving up here. Before I give the BMW "stealer" $100 bucks to tell me what it is...any ideas. It is a 3.0i. Most of the posts said folks were having problems with the same codes...HELP. I am 600 miles from home and i dont want to drive back after thanksgiving with the light on

Could be several things from a vacuum leak to a faulty MAF or a precat O2 sensor. Try to push the X in high RPM and see if there is any hesitation. Also Does it show any erratic idle rpm behavior? If the truck works fine and you get good mileage it may be a temporary glitch. In that case I would suggest to clear the code and see if it comes back after some time. Otherwise the dealer will be able to tell you what the issue is for few hundred $ for the diagnostic and more to fix the issue. Before going to the dealer you can try to clean the MAF. That is very easy.

If i clean it what should i use? And if I clean it and that is the problem should the light go out or will it have to be cleared

I'd check the 3 and 5 series forums before going to the dealership since it's the same motor and I'm sure they've already come across this problem before. Bimmerforums, bimmerfest, 5driver, e90post, roadfly, e46 fanatics, etc.

I also found this using my web browsers search - http://repairpal.com/OBD-Code-P0171-and-P0174

Any autoshop will carry some kind of MAF cleaner in spray. I use CRC MAF cleaner myself. Remove the MAF and spray inside. You will have to reset the error code. Autozone can do that for you or you can also buy a OBDC2 code reader from ebay for less than $40.

Don't waste your money on the CRC stuff or add premature wear by "cleaning" it. The MAF is self cleaning by heating to burn off any residue, but if your MAF is going bad, you're only putting off the inevitable. An easy way to test the MAF is to unplug it and see if it affects how it drives in a positive way. Clear your codes, see if it comes back and check the other forums I suggested.

He said that the truck already drives fine and MPG is fine so how would disconnecting the MAF help to see if it runs better? MAF cleaner has helped me on a couple of occasions.

those codes read system too lean in bank 1 &2. your not getting enough air or fuel. if your mpg were average than you should look into cleaning the maf sensor. check to make sure your air filter and intake are nice and tight free from leaks. goodluck

I know, that's why I suggested he unplug it and see which way it affects it. If the MAF changes nothing, then he can move onto the next step. I've cleaned my MAF before w/ positive results also...but its short lived. Its like cleaning spark plugs - you're better off just replacing it. I just finished replying on another thread about using an $87 VW MAF. forums.bimmerforums.com/forum/showthread.php?p=18005540

ITS AN OUT OF SPEC MASS AIRFLOW SENSOR. IT WILL STILL WORK OK JUST OPERATING OUT OF SPEC AT TIMES AS DETERMINED BY THE ECM. CLEAR THE CODE WITH A SCANNER ( ACTRON MAKES A GOOD CHEAP ONE ) IF IT COMES BACK, ITS CONFIRMED. DO NOT ATTEMPT TO CLEAN THE MAF, USLESS EXERCISE & IT MIGHT DESTROY THE MAF. MY 2006 X5 3.0 WAS RECENTLY REPAIRED BY THE DEALER UNDER WARRANTY. SAME CODES, SAME SYMPTOMS. REPLACED MAF, CLEARED THE CODES AND GOOD AS NEW. YOU DO NOT HAVE 2 CLEAR THE TROUBLE CODES AS THEY WILL CLEAR THEMSELVES ONCE THE CONDITION IS CORRECTED & THE VEHICLE IS OPERATED FOR A FEW DRIVE CYCLES ( NORMAL DRIVING ) HAPPY MOTORING..........FRANKIE P.