My A6, 2.8 Quattro failled emissions and the diag showed
trouble code, "P1138 Manufacturer Controlled Fuel and Air Metering".
Last time the engine light came on the dealer cranked me with all kinds of repairs!
Any suggestions?

 

vacuum/ air leak check all the air/vacuum pipes for cracks

 

P1138 17546 Fuel trim too lean at idle (bank 2)

Check for vacuum leaks on left side of engine,
driver's side US.

 

Your MAF sensor is dirty I think. You clean it with a electronic part cleaner. Make sure, it dry very well before you start the car. use vagcom or something to get rid of the CEL. drive a while see if it make different.

 

Ill see if I can locate the vacume leak. In other news the "check Engine" light went out a few days ago and it has not come back on. Would anyone think that I should just take it back for the retest on the emissions or try to get somebody to look at it on short notice? The tester guy said I would have to drive it 120 miles to clear the trouble code. Is that right?
Thanks

 

It could take longer than that to clear the code. Go to autozone and have the code cleared. Then drive for a while. If the light doesnt come on go to emmissions.