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Discussion Starter · #1 · (Edited)
Whats up all. I recently purchased my first bimmer, a 1999 540iA. The car has just over 67,000 miles on it, and appears to be in great shape besides some minor cosmetic problems.

anyways, last night driving home i noticed a few problems, and was wondering if you could help me ease my stress perhaps haha. First, the "service engine soon" light is on, which i sadly neglected to notice when i was test driving it. However, no other warning lights are on, and the car drives like a DREAM (besides the other problem (?) which ill get to in a minute). I called up the previous (original) owner, who serviced the car 300 miles ago, and he said the light has come on in the past and that he thinks its just a faulty sensor. From reading previous posts, i think i should take the car into the shop so they can read the code, but is this something that needs to be done RIGHT away, or can i wait a bit. in other words, do you think this is a symptom of some big problem?

The next thing is transmission related. so far in my driving, SOMETIMES when i slow to a stop at traffic lights, as soon as my car is completely stopped i will feel a small jolt, like the transmission dropped..but it doesn't feel good. Maybe this is normal...but i wouldn't know because im used to driving honda 5 speeds and have never owned an automatic. This problem only happens sometimes, and i noticed is more likely to happen if i was going fast and came to a stop rather quickly. If you guys don't really understand what im talking about, i can elaborate further

Really, right now i'm a newb and sorta freaked out because i dropped bank on this car and want to make sure it's running smoothly. Any and all feedback and help is appreciated more than you can know

thanks alot!
 

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The SES light is almost never "faulty," so you can rest assured that there is a problem somewhere--maybe very minor; maybe very major. Get the code checked; you can borrow a code reader from Autozone; don't go to the dealer unless you have no other options. I would purchase your own code reader/resetter, though. Best tool for your BMW that you can buy. I'd venture a guess that the SES and the auto transmission problems are related. Also, look into getting your cooling system overhauled as a preventative measure. Anyway, congrats on the purchase! They are great cars....
 

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Discussion Starter · #3 ·
thanks for the reply waveho...very helpful

so im going to borrow the codereader from autozone. if the problem ends up being minor, and i fix it...do you think i can rest easy? i say this because it seems like theres a sensor for all problems in this car, so if there was a tranny problem wouldn't the car alert me of it? or am i wrong? haha thanks.
 

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Discussion Starter · #4 ·
ugh

so i went to autozone and pulled a P0171, System Too Lean (Bank 1).

from OBD codes:

A code P0171 may mean that one or more of the following has happened:

* The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
* There could be a vacuum leak downstream of the MAF sensor.

Basically this means that an oxygen sensor in bank 1 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1.

going to the shop today
 

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Don't go to the shop quite yet! Get some throttle body/MAF cleaner; remove and clean those areas and check all the hoses in and around the MAF for any breaks or tears. Also, your model probably also has an Idle Control Valve; remove and clean that too. Reset the codes and drive around a bit to see if it reappears.

If that doesn't do it, I would replace the Bank1 pre-CAT O2 sensor--another simple DIY job and the part is about $100; these are prone to going between 60k and 100k miles. I would do all this before thinking of going to any shop for this particular problem.

Instructions for doing most of these job are on this site, in the 5-Series DIY forum, or go to http://www.bimmerdiy.com/dir/e39 for some good info. The more you learn to Do It Yourself, the more $$ you'll save. Much, much more.... Good luck!
 

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Discussion Starter · #6 ·
hey, thanks again for helping out my bmw ignorance! i wasn't able to go to the shop today, luckily, so i'll be cleaning the areas myself. anyways, how do i reset the codes for the car? thanks again
 

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Unfortunately, the diag. tools usually available from Autozone are "read only," and are not of the variety that allows a user to reset codes, reset the oil change lights, etc. Local shops may have one they can loan for that purpose, but I'd avoid letting them charge you for their use. Dealers charge a good amount just for this service! I bought my Peake code reader/resetter on ebay for about $100. Good luck!

(Most CEL codes will eventually reset themselves after a while if the problems are fixed and do not recur)
 

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Discussion Starter · #8 ·
dissasembled the MAF sensor, cleaned it with MAF cleaner, put it back together. after about 70 miles of driving around the SES light turned off. Thanks again for th egreat help waveho :). only cost me $6 for the fix
 

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dissasembled the MAF sensor, cleaned it with MAF cleaner, put it back together. after about 70 miles of driving around the SES light turned off. Thanks again for th egreat help waveho :). only cost me $6 for the fix
Hey no problem! Glad I could help. There's a ton of good DIY info on this site that I'm still only starting to absorb myself. I plan on replacing my headlights in a couple days--I'm very bad with electrical connections, so this will be interesting.
 
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