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How many oxygen sensors on a 1997 4.3 X VIN

29K views 15 replies 5 participants last post by  MyWorkInProgress 
#1 ·
And where are they located. I had a diagnostic test done at the local Cherolet stealership and they said I needed a O2 sensor replaced in Bank 1. I took it to Pep Boys and they supposedly replaced it for half the price of the dealer ($125) Now my check engine light is back on for an O2 sensor again. What are the chances it's a different one or Pep Boys replaced the wrong one? It's has 50,700 miles on it. I'm asking because if it has 3 O2 sensors, for the $255 the dealer wants for one, I can just have Pepboys do two for that price. ActuallyI can do the one on the drivers side above the spark plugs. Hopefully there is only 3 total.
 
#4 · (Edited)
There is even a chance the sensor wasnt bad. The first thing any of these places do including a dealer is to replace the sensor that coded and thats a 50/50 at best workable fix. Sensors just tell you more times than not, what there seeing, not that there bad.

Need to code!!

Yes this bank 1 and bank 2 thing has many confused cause on a Ford there reversed. So this guy at Pep boys thinking Ford may have replaced the wrong one.
Plus back to the code, was it rich, lean, or circuit prolbems.

Rich could be and injector problem or a bad reading from the MAF making the comp send it to the rich side cause thats what the MAF reading indicates it needs. Its reading outside the predetermined program perimeters and all the 02 is saying is its rich, it cant fix the problem. Same thing on the lean side for MAF improper reading versus the program. Vacuum leaks help the lean code and so on. Circuit problem can be a simple as a bad connection or chafed wire to a OBD going brain dead and not delivering the proper outgoing voltage, but the OBD doesnt know its doing that.

See changing a sensor just cause it coded is like pissing in the wind, you may get away with it, then you may not. Service techs really need to learn why, what etc a code is and stop this changing of the sensor crap, like I said is 50/50 at best!!
 
#5 ·
On-board diagnostics (OBD) II is making it easier than ever to diagnose cars. Well ... maybe not. But it is giving us information that can help pinpoint a problem with more accuracy and less time invested.

How do they count O2 sensors? Where is Bank 1, Sensor 3? Or ...Where is Bank 2, Sensor 2?” When thinking of O2 sensor positions, let's start with a single exhaust system in, say, a 1998 S10 Chevrolet pickup truck with a 4.3L Sequential fuel-injection engine. These trucks use four O2 sensors, but which is which?

Bank 1 is always the bank where cylinder No. 1 is, or in this case, the driver's side (left) bank, and Bank 2 is the opposite (right) bank. After the point where the pipes meet, everything is Bank 1.

Now, counting O2 sensors. One is located by the left manifold, which is Bank 1, Sensor 1 (scanner shows B1-S1). Moving back, the sensor in front of the catalytic converter after the Y-pipe is Bank 1, Sensor 2. After the Y, it's all Bank 1, but we still count the sensor in the manifold as 1. So now the sensor behind the catalytic converter is Bank 1, Sensor 3 (scanner shows B1-S3).

Helps to have a scanner!!
 
#6 ·
Thanks for your input. I thought thats why the dealer was going to do, find out why the SES light was on and what the problem was. Instead they are saying there is no problem, I just have a bad O2, which could be considered maintanence.

Other then the light coming on, the engine sounds and runs smooth. I plan on having the fuel injectors cleaned and I was about to change the spark plugs when I realized after pulling one out, that they have been changed once already and it only has just under 51,000 miles. The air filter is clean and I will soon change that to a K&N. Is there some other things that could trip the SES light and not be noticable.

My take is, the techs these days are not true mechanics. If it doesn't come up on there fancy little diagnostic machines, they are lost. When all fails, they say, " could not duplicate problem" or "everything seems within normal specs"
 
#7 ·
That's the one they said needed replacing, Bank one sensor 3. I wonder if that is the one they replaced. That one certainly can't be that hard to replace. What does that sensor detect?

You information has cleared up alot of things about the placement of these sensors. That was the main thing I didn't understand. I didn't know what the hell the Bank one Sen 3 meant. Would I be able to tell from looking at the outside if the sensor if it was chanced in the last 3 or 4 weeks?
 
#8 ·
If I read that right, what you just posted its bank 1, sensor 3. HAHAHAHAHA dont mind me!!

The only job of bank 1 sensor3 is to check on how the cat is working. I even like GM coding to confuse the so-called techs.
PO141 OXY sensor circuit- Bank 1 sensor 3
PO143 OXY sensor circuit lo volts- Bank 1 sensor 3
PO144 OXY sensor circuit hi volts- Bank 1 sensor 3
PO145 OXy sensor slow response- Bank 1 sensor 3
PO146 OXY sensor no activity- Bank 1 sensor 3
PO147 OXY sensor heated circuit- Bank 1 sensor 3

Yup change the sensor first thing, cant decipher what this crap means.

First thing if I was doing it. Grab my sensor tester and test the sensor, is it bad or not??
Second would be check the wires for breaks and chafes etc.
3rd would be use my trusty pressure gauge for this purpose and drill 2 holes, one before the cat, one after and take pressure readings, and increase after the cat shows the cat is plugging.

What did they do, plug in there $75,000 Diagnostic center, read code, scratch balls, determine change sensor!!
As you can tell I have a great respect for ASE techs, NOT!! Its my hobby and I can do better than they can, I didnt sit in a classroom snoring and get my ASE badge. I have to quickly fix things for thw lowest cost, they dont etc!! Here print my post and show it to them, see how red they get!!
 
#9 ·
supercobraz said:
Would I be able to tell from looking at the outside if the sensor if it was chanced in the last 3 or 4 weeks?
Yes you should be able to. These dont comeout easy, so the one they changed should show signs of struggle near it, cleaner around the thread portion and also heat changes the color of them so this one would be alot cleaner looking!
 
#10 ·
Thanks man, I'll take a look after work and see what I find out. Or I may just stop by Pep Boys and ask which one they changed. I can change either one of those myself in the future. If I had the time and asked these questioned prior to taking it in, I could have saved about $65 in labor.
 
#12 ·
Are there any signs that the Cat is "plugging" other then to do that pressure test? Will any of those codes tell anything. All those codes sure can be confusing, but putting on a new sensor will not fix the problem if the sensor itself is not bad. Man, it pays to know how to a little something for yourself. I'm getting better at it myself though.
 
#13 ·
supercobraz said:
Are there any signs that the Cat is "plugging" other then to do that pressure test? Will any of those codes tell anything. All those codes sure can be confusing, but putting on a new sensor will not fix the problem if the sensor itself is not bad. Man, it pays to know how to a little something for yourself. I'm getting better at it myself though.
Sulphur smell. If youve run your hand over your tailpipe before and now notice not as much force is there at idle. You can home kit the pressure test. Drill a hole about 1/8th before the cat and get a good feel of force coming out, tape seal it and one rear of the cat and feel force. Semi plugged maynot present itself too much, but more than semi will!! Or use a $19 vacuum gauge and be creative to seal it to the exhaust, they do come in handy alot for $19!!
 
#14 ·
Everything smells normal and I'm not sure about the pressure before but it seems about normal as well. I'll just first find out which sensor was changed and go from there. I'm just getting tired of seeing that SES light. Plus I would rather be spending my money on some other things for the truck then chasing down the source of this problem.
 
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