NEED HELP QUICK: 97 SOHC (Ex Limited) 02 sensor

[410Fortune]

Okay we have a 97 Limited (SOHC 4.0L) with a CEL.

Code says 02 sensor bad, w-2

Anybody know which 02 sensor is W-2?
There are 4 on this truck

Thanks!

 

[Glacier991]

What code number is associated with this ?

 

[410Fortune]

Thats what I would like to know too...unfortunatley this is a freind struck and he had another friend pull the codes, all we know is 02 sensor bad, w-2

He is planning to replace all 4 to the tune of $220...I was trying to save some $$$$

 

[Nate1]

He only needs to replace the two before the cats at most. They are the upstream sensors and actually send some data to the computer to control emissions.
I cant tell what bank that is though.

 

[Alec]

I'm thinking driver side, but could be wrong.

 

[Glacier991]

Just a heads up... an O2 sensor code does NOT necessarily mean the sensor is bad. It simply means the readings coming from it are not within expected parameters... lots of other things can cause this, so do not just go blindly replacing $75 sensors unless and until you have explored what could be making the sensor read bad. And FYI the upstream (pre cat) sensors are used for short term fuel trim. They fluctuate across a .445 volt threshold. The post cat or downstram sensors are used to see how the cat is doing, and usually flatline at a higher voltage when the cat is operating properly... the PCM compares the two, so while it is not wholly inaccurate to say the upstream sensors are used to evaluate the CAT, it's really the downstream that do that.

Happy Exploring

Chris

 

[410Fortune]

THANKS for the replies, I am aware that an 02 sensor code doesnt mean the 02 sensor is bad, believe me.....

It turns out there are 3 02s on the 97 SOHC.
He replaced all 3 and so far so good.........

the two upstream of the cat are the same with the single after the cat being a different 02 sensor. all bosch from Ford.........

Expensive maintenence!!

 

[Robert]

Your obviously not talking about a '97 Explorer SOHC then, since all '97s have 4 O2 sensors. One each in front of each catalytic converter, and one each behind each catalytic onverter, just before both pipes go into the muffler. Several years later Ford went to a single inlet muffler on the SOHC but that was around 2000 or 2001. On those it is likely that they only have 3 O2 sensors, but not the '97-'99s.

If your Friend's Explorer only had 3 O2 sensors then it would be the OHV and not the SOHC. The '97 OHVs had two cats that were in line with each other. On those they had a single post-cat O2 sensor between the last cat and the single inlet muffler.

 

[410Fortune]

You are correct sir, I was under the truck with him last night and it indeed does have 4 02 sensors, seems the Ford dealer only supplied him with 3 and charged him for four......so we replaced the 4th one last night.....

 

[dannodet]

Question for this group. How did you get to the passenger side, pre-cat, 02 sensor? I can see it, I can touch it, but I'll be danged if I can get the special 7/8 deep socket w/ groove for the wires on to the sensor. Then there will be the delema of how to get the socket wrench in there with enough room to actually turn it! Any suggestions would be appreciated before I crack my knuckles!