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Discussion Starter #1 (Edited)
I had a lean code on the first bank P2096. I took the car to a dealer for diagnostics, dealer gave me an estimate for $1,700 to change all 4 O2 sensors, without ever doing the diagnostics, but wanted to charge me $180 for it. After I questioned the mechanic, he admitted that he really did not do the diagnostic, but said that the code is typically O2 sensors, and often comes back and that it could be something else ??? Made no sense to me, since the code was on the bank 1 only. I refused to pay them.
So I decided to deal with it myself. I threw a bunch of money into parts since I did not have a good diagnostic tools. I changed front and back bank1 O2 sensors, then intake gaskets, throttle gasket, PCV hose/tube, inner Disa new spark plugs, rotated coils between the bank 1/2, smoked the intake at least 3 times, smoked the muffler for gasket leaks and ultimately replaced valve cover with gaskets [ with new built in CCV ] and new gasket on the valvetronic motor and on the sensor. After each replacement I cleared the codes, drove the car for 10 +/- miles and got the same lean code, at least as a pending code. One thing I noticed though with the limited tools I had, was that the Long term trim on the secondary O2 sensor of Bank 1 was at 44.5% and never changed at all, stayed the same even after each part replacement. The short term trim numbers looked really good to me., had fairly small variations. So I started to wonder if that was not the cause for throwing the lean code, maybe it was taking that big number into the calculation when tripping the code. I called some guys that deal with BMW's, but no one thought that was the problem. Eventually, after I replaced all the parts mentioned above and still was getting the lean code, I went to a local guy that works on BMW's and had him reset the DME adaptations. Sure enough, no more lean codes, no pending codes. Just to say, I think the crazy number was locked in there due to old spark plugs, that had over 110K on them - both the car used. Engine misfired few times when my wife drove it, had bad starts etc. and I think that was the whole problem. We drove the car for several months with engine light ON since I had no time to deal with it. I only changed the spark plugs after I started to diagnose the issue and that might have been all that I needed really done.
So check your long term trim on the bank that is throwing the code, if it is way out of whack, you might need to reset the adaption after you replace what you find to be a faulty part, before going on to the next step and spending unnecessary money .
Hope that it helps someone
 

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Good chance you have a vacuum leak. What year/engine?
A smoke test is in order.
 

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. I called some guys that deal with BMW's, but no one thought that was the problem. Eventually, after I replaced all the parts mentioned above
Folks who don't know what A 44% long term fuel trim is don't have any business fixing cars

This is basic stuff
 

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Folks who don't know what A 44% long term fuel trim is don't have any business fixing cars



This is basic stuff


Truth.

I still run mostly carburetors and even I know that ish!


Sent from my iPhone using Bimmerfest mobile app
 
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