O2 sensor question

toxicpelican

New Member
Jan 30, 2006
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the car in question is a 95 Gts, it should have 2 heated o2 sensors right? where are they located in the pipes?

1 of mine has gone bad, according to cel and the shop i take it to, they want to go through ford directly for a replacement o2, which will prolly be overpriced as usuall. id prefer to supply my own o2, what part # or brand should i use when going to the local parts places?

thx
 
They are located in the exhaust just ahead of the cats IIRC. Changed mine a couple of years ago with NTK-22016. They are a consumable in the sense that they do go bad over time. I would recommend that both be changed at the same time.
 
If you have a 7/8" wrench, some lubricant (like PB) and 5 minutes, you can swap one out yourself.

As Toyman stated, we do have HEGO's (heated EGO's) and Bosch, NGK and Ford are all fine sensors. You can get them for under 50 bucks each.

Good luck.
 
My stock O2s were made by NTK which is NGKs line of oxygen sensors. I got replacements from Summit cheaper than I could find at any local parts house; you might find the same thing out.

http://store.summitracing.com/partd...&part=NGK-23120&N=700+401124+115&autoview=sku

Those are the ones I used, NGK-23120, and the only difference between those and the stock ones were the pigtail was longer, which is nice.

http://store.summitracing.com/partdetail.asp?autofilter=1&part=NGK-22016&N=700+0&autoview=sku

There's the ones toyman listed just for the hell of it. I haven't used those so I can't comment on them.
 
ok well i just went out and looked, i see the o2 on the driver side just before the 1st cat, and none downstream, ill assume that the other one is just before the 1st cat on the passenger side. they dont look overly fun to get to, would you suggest trying to change it from above? or front under with the car on ramps?

also. i pulled the codes again (on my $30 actron scanner), it gave me:
172 - HEGO sensor indicates lean, bank 1
176 - HEGO sensor indicates lean, bank 2

whereas the guy at the shop who pulled codes on a much better(?) scanner gave:
PO172 - bank 1 no switch system lean
PO136 - bank 2 no switch

the guy at the counter told me that they wanted to change 1 o2 sensor, as it wasnt switching, and the other one seemed fine... does this sound right? if so, should i go with what their scanner said and just change 1 sensor? which one do i change? ($$ is kinda low right now, so if i only need to replace 1, id be better off that way)
 
ok well i just went out and looked, i see the o2 on the driver side just before the 1st cat, and none downstream, ill assume that the other one is just before the 1st cat on the passenger side. they dont look overly fun to get to, would you suggest trying to change it from above? or front under with the car on ramps?

If you do it from on top, have someone take pics because that would be a new one on us. The sensors are right in your face when you're under the car.


also. i pulled the codes again (on my $30 actron scanner), it gave me:
172 - HEGO sensor indicates lean, bank 1
176 - HEGO sensor indicates lean, bank 2
Now we're getting somewhere. Both O2's taking a dump is not likely. You very well might have a vac leak, MAF issue, etc that is causing both sensors to be providing feedback different than they should be.

Be sure you have no vac leaks before replacing O2's.

whereas the guy at the shop who pulled codes on a much better(?) scanner gave:
PO172 - bank 1 no switch system lean
PO136 - bank 2 no switch

These are OBD-II codes, which are incorrect for a 94-95 V8 Mustang. I would disregard these codes. The codes you pulled above are what matter.

the guy at the counter told me that they wanted to change 1 o2 sensor, as it wasnt switching, and the other one seemed fine... does this sound right? if so, should i go with what their scanner said and just change 1 sensor? which one do i change? ($$ is kinda low right now, so if i only need to replace 1, id be better off that way)

If one sensor actually is not switching (or has lost considerable frequency and amplitude), then it can be ok to just do one. I always confirm the readings with a DMM (It takes 2 mins to do). Then you know exactly what the O2 is doing. In your case, I still dont think the O2 itself is the issue since you're spitting codes for both banks. That indicates a systemic issue (aforementioned vac leak, etc).

Good luck.
 
JT said it all too well :hail2:

Especially the part about both O2's showing a code :nice:
thus
Something is hosed causing a prob common to both banks
which
Just as our Wise Ole Wizard ... Mr. JT has given sage advise

Guys ... Things such as this is where common sense is your friend :)

If you got only one O2 throwing a code :scratch:

You can swap banks with both O2's for a test
and
If you then get a code for the other bank ......

Your little self test has verified your suspicions of a bad O2 :D

Grady
 
You guys know that issue to well:)

I do want to add, that when I bought my '98 (got a deal on it), it had been wrecked several years back and hit in the back. This ended up damaging 3 of the 4 02 sensors.

I replaced them about 15-20,000 miles ago and no problems.

So basically what I am getting at, was your car wrecked or the H-pipe hit hard in the past?

This scenario is very unlikely, and I would be willing to bet that it is more related to what JT and Grady said:nice: Take their advice...
 
You guys know that issue to well:)

I do want to add, that when I bought my '98 (got a deal on it), it had been wrecked several years back and hit in the back. This ended up damaging 3 of the 4 02 sensors.

I replaced them about 15-20,000 miles ago and no problems.

So basically what I am getting at, was your car wrecked or the H-pipe hit hard in the past?

This scenario is very unlikely, and I would be willing to bet that it is more related to what JT and Grady said:nice: Take their advice...

Very good points David :nice:

Also ... Don't bang on them or allow them to get a whack from a wrench,
socket, or anything else while working on things that might be located
near them as they could be damaged and they ain't cheap :D

They just need to command a bit of your respect and kinda be
considered a bit fragile :)

Grady
 
If you do it from on top, have someone take pics because that would be a new one on us. The sensors are right in your face when you're under the car.

These are OBD-II codes, which are incorrect for a 94-95 V8 Mustang. I would disregard these codes. The codes you pulled above are what matter.


Good luck.


+1, There's no way he should have even gotten those codes. Did he plug the scanner in under the dash, if so he should have gotten an error when doing so...
 
yea i have no idea how they came up with those codes, im going back on monday and insisting that the do the diagnosis correctly this time.

(ive already checked around for vac leaks, cleaned maf, etc, cant figure out whats going on with it, letting them figure it out, and then ill fix it)