Originally posted by JimRome25:
I originally had a post about getting the code P0171, lean, bank 1. I have replaced both O2 sensors withing the last year, cleaned the Mass air flow sensor, and have changed the fuel filter.

I have a K&N air filter and a tornado in the car right now. Thinking back, I never had this problem when I bought the "Pre-oiled" brand new K&N. These problem arose just after last summer after I had re-oiled the K&N. My question is would a improperly oiled K&N cause this due to lack of flow or some oil build up of some kind, or is this a chance event that is not related? Keep in mind that I cleaned the mass air flow recently.

Other ideas I had:
Bad engine computer
Clogged Injector

Aside from the poorer gas milage and the engine light the car runs normal!

Sorry for the long post.

Thanks,
Jason



Called Autozone for you since around here it is open 24 hours.... PO171 caused by

- faulty O2 sensor
- dirty MAF
- vacuum leaks
- intake leaks

First place I'd check ( since you did the first two) is the PCV hose very common place to have a crack.

I had PO171 and was getting terrible gas mileage, replaced downstream O2 and cleaned MAF and codes gone mileage back up.
Just checking you removed the MAF when you cleaned it right, that is how you do it the correct way.
Also are you sure you didnt damage it?

There is a TSB out for this code PO171 it says the MAF may be dirty.