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maf problem? code p1071 p1073

7K views 7 replies 6 participants last post by  Mayorchuck 
#1 · (Edited)
First off its codes p0170 and p0173. Well my e38 runs great idles right around 600 rpm. purs light a kitten. I just bought the car had everything check over and everything was good. I drive 200 miles home and the next day those codes come on. I sprayed carb cleaner around intake gaskets but no effect in idle. I then took off maff and cleaned it. The engine light stayed off for almost 300 miles. Do you guys think the maf is bad? Oreily said the fixes are intake gaskets a maf sensor or vacuum leaks. but I don't get a lean code.
 
#3 ·
When I first got the 740 for my wife, I had the leaky boot, rough idle, white smoke and had already determined to replace ALL rubber and plastic gaskets, caps, hoses, osv, etc, to eliminate all questions since the intake system is so involved. After doing so, all was well, Passed CA smog test "hands Down" and still original MAF.
 
#6 ·
Keep in mind that all codes from past or present are stored until they are cleared. If you have not had your codes cleared recently, I would do so and check them again after a drive. MAF are more often than not caused by a dying MAF. If can be caused by vacuum leaks so after verifying the code, it always best to check for leaks:

 
#7 ·
I just had the same codes on my 2001 740i

P0171 - System Too Lean (Bank 1)
P0174 - System Too Lean (Bank 2)


Spent hours trying to find a nonexistent vacuum leak - everything looked good, no idle changes while coating vacuum leak zones with carb cleaner, etc.

Cleaned the MAF (Mass Airflow Sensor) with electrical contact cleaner - to no avail. I had cleaned this sensor a few years back, and it actually got my 'Service Engine Soon' lamp to go out, but not this time around.

******THE FIX*******

Realizing that the fault codes pertain to both banks of cylinders, I decided to just replace the MAF, and you can achieve this for the cost of a tank of gas...

The factory Bosch BMW replacement part costs about $300.

After some research - mostly within Bimmerfest (THANK YOU!) - I found that a cool suggestion based on part interchangbility actually works!

The interchangeable sensor in question is meant for the VW Beetle, Golk, and Jetta MkIV. Here is a link for the specific item:

http://secarpart.com/products.php?product=Mass-Air-Flow-Sensor-%2d-06A906461A

You will notice that the factory Bosch VW MAF is much smaller than the factory Bosch BMW MAF. The actual sensor, though is the exact same and can be extracted from the VW unit by removing the (2) torx head security screws holding it in place. These look to be FIVE-point torx-plus security screws, about 25mm. I do not have those bits, and carefully removed the screws with some knipex pliers.

After removing the faulty MAF from my 740i - held in place with (2) torx security 20mm screws - I inserted the VW Bosch MAF into the orifice and seated it down with the BMW 20mm torx security screws. After plugging in the MAF harness I started the car and needless to say I was very pleased with the results - even more so after test driving.

The throttle response on ALL levels of the power band is now consistent and crisp. The hesitation I would experience when flooring the vehicle is completely absent and the acceleration is back to 100%.

Would definitely like to thank the member whom posted the alternative Bosch part suggestion earlier in the forum. It is a logical fix that saves you a lot of time, money in aimless shop hours, and remedies a car that does not perform as it should based on vague OBD fault codes.

Good luck - hopefully this helps!
 
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