2001 ford f150 4.2 6cylinder
 

Howdy, I have been having problems with the check engine light. took to get smog. it passed on all but the OBD. the codes 0171 and 0174 are the problem. I've had new spark plugs and wires, EGR, PCV, O2 sensors, fuel filter and intake manifold gaskets(upper and lower). some other things too. the check engine light is still on. The last mechanic told me it's electrical. he doesn't repair electrical. It's now at another repair shop and I'm now being told it's the intake manifold. I just want my truck fixed so it will pass smog and I can get my plate tag. Anyone out there ever have this problem. I don't want to be taken for a ride(at least not this kind). please respond!

A Ford P0171 is a LEAN code for cylinder bank 1, and P0174 is a LEAN code for cylinder bank 2. These codes commonly occur on many Ford vehicles, and are set when the powertrain control module (PCM) sees the air/fuel mixture is running too lean (too much air, not enough fuel).

f the problem is not enough fuel, the underling cause may be a weak fuel pump, restricted fuel filter, leaky fuel pressure regulator or dirty fuel injectors.

More info on what causes the problem can be seen here.

Clean the MAF first and see if that helps. You can pick up some Mass Air Flow Sensor cleaning fluid at your local auto parts store. Once you've cleaned it, clear the code by disconnecting the battery for 10 to 15 minutes, reconnect and start your truck. If you throw the codes, then time to check the fuel system, etc.