simply stated. need to know bc i keep throwing 170 and 171 codes. i changed my after cat one and it helped a little but not a whole lot

 

Please post the whole code and which engine/ year you have. Then we might be able to answer reasonably.

 

those are the codes 170 is a fuel interupt and 171 is too lean. im more less wanting to know what cylinders the pre o2 sensor determines for the fuel

 

your o2 senors help to determine your long term and your short term fuel trim for all cyclinders. Just because you have an O2 code showing up it's a bad idea to start condeming o2's....gets expensive fast. If your getting a lean code, chances are your not having an o2 issue it's more related to a cyclinder actually leaning out...possibly a plugged fuel injector. What do you other guys think?

 

Could be MAF, air leak, vacuum leak or dirty injectors.

 

well it the rear 2 cylinders im having the trouble with. what is some good stuff to clean my injectors with

 

What engine do you have? On the 1.8t the precat o2 monitors all 4 cylinders. On the V6 there is 2 pre cat sensors. Each one monitors one bank or side of the engine.

 

o ya sorry it is a 1.8t. well then what would be causing me to have the rear 2 cylinders fowling out the plugs and getting those codes?

 

P0170 - Fuel trim malfunction (bank 1)

P0171 - System too lean (bank 1)


Have you checked your oil filler cap? Broken oil dipstick?

Intake Air leak?

MAF sensor??

Faulty 02 sensor?

No way I can pinpoint what it is exactly. You are going to have to do some elimination.

 

Jest,
Could this also be caused by a DV going south?