Everything seems to pass except "107" diag. of fuel supply test...

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-00 S4 Tiptronic w/ APR chip in "STOCK" settings, APR bipipe, APR CAT back exhaust. Trying to get my readiness code back to all zero's, all tests the Bentley CD says need to pass for new readiness code, EXCEPT when I get to "107" (diagnosis of fuel supply test)...GET "SysNok". I've run 3 different 3/4-full tanks w/ 93OCT from Exxon, Mobile, and Texaco, and cleared all the codes prior to testing. ALL The other tests Bentley's says to do for regeneration of readiness code pass. Here are the results of "107"...DTC 17519 O2regulation Bank1 system too lean 35-00-- AND DTC 17555 O2 control (BAnk 2) system too lean 35-00--. Engine @ IDLE (760-800rpm): "O2 CTRL1= 18.8%-19.5%"..."O2 CTRL2= 17.2%-18.8%". I see that the highest value should only be 12%max. The car has days where it seems fast, and other days it isn't. I bought a new Bosch MAF sensor from the dealer, haven't installed yet, but hoping that replacing it will perhaps change these numbers and make those 2 intermittent DTC's go away. Any assistance is much appreciated...Thanks, Chris

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