First off, a O2 code does not mean that the sensors are bad. The computer is telling your that the o2 sensors are reading outside of spec. It sounds like to me you have a bad Vacuum leak. It is common that the PCV hoses are leaking. NOT the valve on the valve cover, but the hose itself. Follow it and feel for the rubber to be soft or even have chunks missing. Good Luck

 

thanks for the help guys. Can you tell me more specifically how to look for PCV hose leaks? I really am not good mechanically, but like to try to do some of my own work. I have pretty much ruled out the IAC since I cleaned it and swapped in one from a different truck, and it seemed to make no difference. So O2 sensor or vacuum leak is probably the issue...? I'm getting 11.5 to 12.5 MPG, and im hoping if I get this fixed it will get better. Idle seems to be better than it was before also, for some reason.

 

replace passenger side downstream o2 monitor it has a bad heater element also check wiring around that area for a break.. also check for a blown fuse the heater cicuit can blow the monitor fuse, clear codes, pull the positive lead for 10 minutes...

 

Ended up just having my mechanic work on it finally. I think he said the pipe coming off the ?EGR? was broken in half basically. He welded it and that was causing the loud noise and check engine light to show.

 

ok, just kidding. my check engine light came back on. Got the code checked at autozone, still said IAC overspeed. My idle seems fine though, if the IAC was bad wouldn't the idle jump around a lot more????

 

Arriving late on the input, I like what ricofalltrades said back on 12/13. The poor little 02 sensor gets blamed for everything. Need to look else where for your answer. As he said look for a hole in the PCV line.

 

Damnit you mean I spent 60 bucks on nothing? got the same problem 02 sensor heater circuit malfunction bank 2 sensor 1. driver side upstream sensor, replaced it, lights still on. truck still has a random what feels to be a major miss and almost causes the truck to die shortly after warmup, but it doesnt do it after its been running....cleared code, undid battery for 30 mins and code popped back up after i started it.

 

I have worked on Fords for years and I constantly see the same type of vacuum leak. I am not saying that is could not be other things, however I see alot of the PCV hose degrading and causing the leak. If you follow it from the RH side of the valve cover (engine right) and it should lead (by should I am assuming you have the 5.4l or 4.6l that has that style) to the back of the engine near the bulkhead (aka firewall) next to the throttle body. You cannot see the hose (unless you have eyes that poke out like crabs)(not the crabs that itch, the ones in the ocean) however you can feel the hose. It will feel soft and will stretch out. If it does, it is bad! Replace it. Will not take about 5 minutes to check.

 

When I first bought the truck I noticed the PCV valve hose was broke, so I replaced it, light is still on to this day, is there another hose to look for?

 

why is my 2001 f150 running lean on bank 1