'99 F150 4x4 w/ 5.4

Need to reach the upstream sensor on the passenger side. Any tricks?

 

Try removing the wheel and inner fender. The sensor isn't usually too bad to get at from underneath, but the connector is buried way up against the back of the cylinder head.

 

ensure you get the special socket for the o2 sensor it has a cut out so the wires can go through then you can get a breaker on it. It is tight but can be done.

Lance

 

I jacked up the truck using the frame so the wheel dropped as far as possible then took the wheel off. I did not have to remove the inner liner, just bend it some. I cut a 1/4" section out of a cheap boxend wrench (19mm?) for the O2 wires and it worked perfect. Good Luck

 

How bad was your fuel economy with the bad O2 sensor? I think mine needs changed (check engine light is on, but it throws too many codes due to the bad ABS modules and sensor which isn't going to be replaced), and am wondering just why I get 11 MPG on a 4.6, LOL.

 

6 months ago truck wasn't idling very good but ignored it. 3 months ago something in the cat burnt or broke so I had to replace it (no code?). Several weeks later got a code for the upstream O2 sensor passenger side and replaced it. Several weeks later idle got real bad so I replaced the IAC. During this whole time I was getting 11-12 mpg city. The last 2 fillups I got 12-13. So my mileage improved but it's still terrible. The truck certainly runs better but I don't know if 1 or all 3 helped the mpg.