Hi

I have 96 Audi A4 2.8 Quattro 115k miles.

The CEL came on with the following code: 16558 P0174 Fuel Trim, Bank 2 System Too Lean. I cleared the code but it came back again. The car backfires quite a bit when deacelerating. Other than that it feels fine maybe a little underpowered. I ran some Techronfuel system cleaner andalways used premium gas. I did the air filter and the spark plugs recently.

Any suggestions?

 

mass air flow meter

 

Vacuum leak.

 

Thanks for the input guys.

How can I rule out mass airlow meter and vacuum leak?

Thanks

 

O2 sensor maybe?

 

Usually it's the mass air flow sensor. Not knowing that motor wellit could also be the upstream 02 sensor. Ruling out the 02's means getting an electrical diagram, disconnecting the harness that feeds the sensors and creating a short at the 02 sensor wires in some manner. There is detailed information on one of the Audi forums, just don't remember where.

 

mostlikely mass air sensor.....mine gives almost the same code but its bank 1 thats too lean ....i took it to the dealer and after i gave them 100 bucks they told me that i needed a new one www.ecstuning.com and you can get a bosh mass air sensorfor i think $115

 

i got mine at the dealer for $80

 

No no no. Before you spend all that money check all of your vacuum lines and all of the hoses and make sure there are no cracks cuts or breaks in them. 9 out of ten cars I see with this is a vac leak. If you dont see anything then I may look to the MAF

 

Had exact same problem, turned out to be a hole in one of my vacuum tubes