2002 Ford Explorer Quick Tune up questions

[vzereeys]

Hi,

My name is Steve and I recently "inherited" this beautiful 2002 Ford Explorer XLT 4.0 SOHC with 201,000 miles on it.

Before its "birthday"

"birthday"

I got the "check engine light" checked out and it seems to be the o2 sensors. It had this light on for a while and never had any of its o2 sensors replaced.

So my question is:

1) should I just replace the one that's faulty or just replace all of them while I'm down there?

2) How many o2 sensors are there for the 4.0 sohc engine? and where are they located?

3) What special tool do I need to replace the sensors?

4) Do I unplug the battery after or before installation to reset the PCM?

5) It never got the PCM upgrade (1U7A-12A650-GMB). Should I do that first or replace the o2 sensors first?

Thank you for the help,
-Steve

 

[Convict1997]

1. I'd just replace the ones that are faulty. O2 sensors aren't cheap.

2. I'm going to guess four. Two for each side. One before and one after the cat.

3. they make O2 sensor sockets that have a split in the side for the wires, but they aren't necessary. An open end wrench will do the same thing assuming you have the clearance.

4. I'd unplug it before you start and then plug it back in once you're done.

5. I'm not 100% on this one but, if it were me, I'd do the PCM after the O2 sensors.

 

[CALDWELL]

the 4 02 sensors are located on the Y-pipe, before / after the cats...

if your gonna replace the faulty ones, I know they arent cheap. You mine as well replace them all while your under there, just because of how much use your X has...

has all the other " PM " components been checked, or are still good ?

I.E - Engine / Trans Fluids, Air Filter, Plugs + Wires, Hoses + Connectors, Brakes


where in Philly are you located ?

I live in Delaware County like 1 mile from the Airport, right off I-95 in Prospect Park.

 

[vzereeys]

Thanks for the answers guys

I live in northeast philly. Fox Chase area. Glad to see another philadelphian

I guess I'll just replace all four of them while I'm down there.

I'll change the fuel filter after replacing the sensors (never remember getting it changed throughout the years).

Then flush out the transmission, tune up, and lastly the PCM upgrade if necessary (idle isn't that bad, hopefully new sensors smooth out the rough spots)

One last question. What sensors do I get for the ones before the cat and after the cat? There's ones with 1,2,3, and 4 wires.

Thanks,
-Steve