I have a 2000 f150 4.2v6, and the engine light came on the other day. I hooked up my scan tool and it gave me rich mixture bank 2(p0175). So, i checked the maf sensor for voltage, good ground, and running voltages. All was fine. I also got the data from the scan tool revealing the 02 sensors were working in closed loop. ie... voltage fluctuations from .3-.8 volts on bank 2. Compared them to bank 1, and yes they indicated a a rich mixture. The engine was running fine for a couple days, then yesterday after the light came back on, i went for a drive and the engine started hesitating. I drove into work this morning, and at first there was a little hickup when I first drove off. But, everything ran smooth after that, and I got to work fine. Any of you guys have any ideas or experience like this. I would like to avoid going to the dealer, but I really dont have the time to mess around with it, without knowing what to look for. I dont want to get into a wild goose chase.
Thanks

 

Clean the MAF sensor with MAF cleaner and carefully wipe clean the 02 sensor.

If that fails, it may be helpful to have a service station preform an emission inspection on the truck and that should narrow it down...