03 silverado Z71 5.3 4x4 200,000. she is throwing a couple of codes. i have the codes and know what they mean, but need to know how to fix.
P0430 cat, below threshhold, bank 2.
P0171 system to lean bank 1 and 2.
any help in where to start would be appreciated. thanks

 

system too lean on both banks usually means feul delivery problem, first place to start would be a new fuel filter and clear the codes. If the problem persists then check your fuel pressure, could be a fuel pump going. About the catalyst, hope the fuel issue resolves both of the codes because then your looking at replacing the cat.

 

i haved replaced the filter about 25,000 miles ago. will check fuel presure and post results. thanks

 

On the 5.3 most likely you need intake gaskets. Fix the codes for lean first if the other comes back you need a cat. PO171 is system too lean bank 1 sensor 1 PO 174 is system too lean bank 2 sensor 1Did you have a PO174 also?