Code P0171 system too lean bank 1 on my 2005 Ford Freestar 4.2L

Question

My wife has a 2005 Ford Freestar 4.2L and has a problem with the air ventilator I think, soon as we turn on the fan it smells really bad, it smells like exhaust or gasoline. I've been working on it like a fuel filter change with a new-air filter change and a new-fuel rail pressure sensor change with new. But the P0171 system too lean bank 1 still showing up. What can I do? Help me.

Answer 1

Hi there,

Since you are showing a lean condition on only one bank, this is usually a result of an intake manifold gasket leak or a bad front O2 sensor.  The bad smell may be a result of having an intake manifold leak as well. With the engine running try spraying some carb cleaner along the intake. If the idle speed increases or smooths out, this usually means you have a leak. This will cause a lean mixture.

Answer 2

P0171 FORD Code - Fuel Injection System Too Lean Bank 1
Read more: https://www.autocodes.com/p0171_ford.html