Does this apply to the 2001 Ford Focus ZX3?

Question

I have a ford focus zx3 that is displaying code P0171. I have replaced the oxygen sensor and still the light is on. Well it just came back on. So next step is to replace the Maf I think. Then the PC valve and check its connections. Then  to the exhaust system. I recently replaced the fuel pump so that should not be the problem I don't think.

Answer 1

On the fuel pump the hose that feed the engine is it properly secured. If you have a scan tool and the fuel trim there is a short trim  and a long trim if the long trim is 20 + the feed line is not properly secure and internally the fuel pump loses pressure/ volume. On Ford the popular is the PCV hose it usually ruptured. and there a vacuum leak as for the MAF sensor Ford recommend use brake cleaner ,

Answer 2

HI there

This code can also be the result of a vacuum leak, typically on these it's at the elbow for the pcv valve, so I would check that before replacing the maf sensor. Yes, the maf sensor can also cause the issue, but a lot of the time it's the elbow.