I need to replace my upper o2 sensor bank one sensor one, where is this located? I have a 98 5.4L 4x4.

 

Bank 1 means it's the side with the #1 cylinder. Sensor 1 means it's in front of the catalytic converter. So look on your exhaust, pretty sure drivers side is #1 cyl, might want to verify that.

 

The O2 sensors on the 5.4 are located right after the exhaust manifold one on each side, also there are two behind the cats but they normally are not replaced. They can be a bit difficult to get at due to the limited space to get a wrench on and very small limited space to reach up to disconnect the wiring harness.

 

WOW, o2 one is the worst one to get to, all the others look managable but not this one. I am going to let a pro take on this task. I think the only way to do this is to unbolt the exhaust at the manifold and drop it down but the bolts are in bad shape and would need to be cut off. I couldn't even get the special socket onto the o2 let alone the wrench.

While there at it maybe I'll also have a set of headers installed .

Thanks for the replys.

 

That's exactly what I did...had my dealer (who I trust) put in the replacement O2 sensors...since I'm only a backyard mechanic (parts changer) I figured they were better equipped with knowledge and tools to do the job right. I was correct it only took them about 90 minutes from start to finish to install the new sensors.

 

My error code said that I was running lead on bank 1. It turn out to be the rubber boot on the back side of the intake that leads to the PVC valve. I would take a look at this first because it only cost about 50 cents to replace it. I only found this out after paying $350 to replace all 02 sensors.

Hope it's the cheap fix
Cya Steve