Oxygen Sensor and Catalytic Converter Questions

curtisckey · Jul 28th, 2005, 11:14 AM

Greetings All,

I have a 1996 Sentra with the CEL on. It has been diagnosed as code P0135, rear oxygen sensor. The car starts and runs great. I understand that this could be a problem with the engine running too rich or too lean or a defective oxygen sensor, or a defective catalytic converter.
I will be eternally grateful if someone with more experience than myself in these matters could clear up a few things for me.

Is there a way to perform the voltmeter test on the oxygen sensor without having to elevate the car and get under it? Maybe if the wires from the sensor terminate under the hood?

The local muffler shop tests the converter by measuring the temperature of the pipe just before and just after the converter. If it’s working, it should be 10 to 20% hotter at output than at input. Is this a valid way to determine if the converter is working?

I’ve also read that if the temperature before and after the converter is almost the same, you should disconnect one plug wire, forcing the engine to run rich, and test again. If it still has equal input and output temperatures, then the converter is not “lighting off” and is defective. Does this seem like a good idea?

Is the only purpose of this oxygen sensor to monitor the function of the catalytic converter?

I live in an area that does not and probably will never require emissions testing. Is it possible to disable the rear oxygen sensor AND keep the CEL from coming back on?

Assuming the converter and sensor are both good, any thoughts on what else would be a likely cause of the problem?

Again, many, many thanks to anyone willing to share their knowledge and experience with this problem.

**wes** · Jul 28th, 2005, 11:34 AM

The rear O2 sensor has NO EFFECT on how the car runs. it is an emissions sensor only. Honestly I would bet the sensor itself is bad. My recommendation is that you reset the CEL and see if it comes back on. IMHO the sensor is likely to fail before the cat....

If the cat was bad the tell tale signs are the egg/sulfur smell.

makaveli · Nov 13th, 2005, 03:35 AM

Quote:

Originally Posted by wes

The rear O2 sensor has NO EFFECT on how the car runs. it is an emissions sensor only. Honestly I would bet the sensor itself is bad. My recommendation is that you reset the CEL and see if it comes back on. IMHO the sensor is likely to fail before the cat....

If the cat was bad the tell tale signs are the egg/sulfur smell.

i know this thread is sorta, and you already dont like me wes.... but stop reading now if your gonna have another smartass comback...

Any way down to the point. cat fail = egg/sulfer smell... well some timess i swear i smell burning hair, could this be the same smell

Quote:

Originally Posted by curtisckey

The local muffler shop tests the converter by measuring the temperature of the pipe just before and just after the converter. If it’s working, it should be 10 to 20% hotter at output than at input. Is this a valid way to determine if the converter is working?

now after ive been driving a while, if i stop the car and jack it up real quick, the exhaust pipe infront of the 2nd cat(ca emissions) is hot and i can barley touch it. but behing the cat it is cool enough(but still warm) to where i can wrap my hand around it and it just makes it feel warm.... plugged cat?

psuLemon · Nov 13th, 2005, 10:20 AM

Quote:

Originally Posted by makaveli

Any way down to the point. cat fail = egg/sulfer smell... well some timess i swear i smell burning hair, could this be the same smell

now after ive been driving a while, if i stop the car and jack it up real quick, the exhaust pipe infront of the 2nd cat(ca emissions) is hot and i can barley touch it. but behing the cat it is cool enough(but still warm) to where i can wrap my hand around it and it just makes it feel warm.... plugged cat?

If your cat was blown, you would DEFINITLY know it, as it would really smell bad all the time. Secondly, he switched the two, the tempature should be less behind the cat as the cats purpose is to elimate gases. Beside the more that it travels, the cooler the air gets.

xbrandonx · Nov 13th, 2005, 10:25 AM

Quote:

Originally Posted by makaveli

plugged cat?

your car would run like total butt if your cat is plugged.

**wes** · Nov 13th, 2005, 11:37 AM

Quote:

Originally Posted by makaveli

i know this thread is sorta, and you already dont like me wes.... but stop reading now if your gonna have another smartass comback...

Any way down to the point. cat fail = egg/sulfer smell... well some timess i swear i smell burning hair, could this be the same smell

now after ive been driving a while, if i stop the car and jack it up real quick, the exhaust pipe infront of the 2nd cat(ca emissions) is hot and i can barley touch it. but behing the cat it is cool enough(but still warm) to where i can wrap my hand around it and it just makes it feel warm.... plugged cat?

Your mistaken... Anyway again I ask why? The car runs OK no? It is not hesitating or down on power? If so why the total analization of everything? I appreciate wanting to know the car, but seriously everything sounds totally fine.

The cat is esigned to do exactly what it is doing, if the cat was totally melted there would be other symptoms and it would throw a CEL sooner or later because the rear O2 would not receive the correct signal.

makaveli · Nov 14th, 2005, 01:03 AM

Quote:

Originally Posted by wes

Your mistaken... Anyway again I ask why? The car runs OK no? It is not hesitating or down on power? If so why the total analization of everything? I appreciate wanting to know the car, but seriously everything sounds totally fine.

The cat is designed to do exactly what it is doing, if the cat was totally melted there would be other symptoms and it would throw a CEL sooner or later because the rear O2 would not receive the correct signal.

well it actually isnt running OK. there are a fair number of things that dont seem to be right. as for the total analization of everything, i contribiute that to this: I live in the middle of nowhere and this car is my life. I work 30 miles away from here(1.25 hour drive) and there is NO public transportation, well except from the end of may to the end of july, and still thats only twice a day. i drive this car around 60-80 miles a day and if somthing happens to it im fucked, ive put everything i have into it, and until im done paying off some (other)bills i have no money to save. Gas alone is fucking killing me, i put about $25 every 2 days.... thats like $350 a month or somthing. Once again i have NO money to pay someone to fix/diagnose this car. hence that constant questions, im trying to learn about this car, so i can do all the repairs myself, if it needs them. If i seem paranoid.... trust me i am. i CAN NOT have anything happen to this car. i hope you understand.... o ya its a 96 200sx Se w/ A/T, A/C, power everything, no aftermarket mods, and 134,XXX miles

With that said....
I really have no idea what is up. i have a couple guesses, but really im clueless. ive done everything i know, and it still is having problems.
If you can, please help..... here are the symptons. i know there is more than 1 problem causing these things, so ANY ideas are helpful.

1.rattles along with little clicks over bumps, but not speed bumps. seems that if both wheels(eather both front or both back) hit bumps no sound. if one does then it makes a rattleing/high pitched clicking(sorry thats the best i can do to describe it) noise.

2.steering feels "loose"

3.it seems to turn easier to the right side

3(a). just had the wheels aligned, but it still pulls rights unless im taking turns fairly quick, then it seems to change the side it pulls to.

3(b). front passenger wheel squeeks, only after the car has been drivin a while, and if i hit a bump some times it stops

3(c) during acceleration from a stop, the wheel rocks left to right(unless im holding it)

4.sometimes there is a vibration from the rear(i think). this is strange, because it seems to vibrate the whole car.

5.if i put it in neutral and rool backward the shit to reverse, there is a loud pop/click in the front end

6.seems to hit bumps very hard, but struts/shocks were just changed

7.at idle there is a loud hissing noise from the rear of the car, as well as the intake

8.brand new yokomo(sp?) 50,000 tires and worn down on the outer edges. i bought them about 6,000 miles/ 2.5 months ago. they're on the front and were put on because i was pulling into the parking lot at work, going about 15-20 MPH, and hit the front right tire on the curb and it popped, goodyear said it was too thin to repair.

9.breaks make a groaning noise when stopping, not the whole time, but only right before i come to a complete stop.

10. sometimes there is a lot of somke soming out the tail pipe, sometimes there is NONE. these happen at weird times too, sometimes it smokes after ive been driving like 1 hour and it sits at idle, sometimes it somkes when i start the car. but the strange thing is that when i start the car in the morning there is NO SMOKE coming out of the tail pipe. also when its not smoking, the sound from the exhaust sounds like the exhaust is Hallow/echoing, and is not very strong. when smoke is coming out, it sounds deeper like it is emminating from the tip of the exhaust, as opposed to somewhere inside the pipe, and it is also alot stronger.

11.Excessive gas consumtion.

12. at idle i hear a low rumble from the steering wheel, but it stops it i move the steering wheel at all(push it up/down, left/right, or in/out, not turn it)

13. somthing(injectors?) under the hood is making a VERY loud clicking noise.

14. after driving for a while if i pull the engine oil dipstick out smoke starts to rise from the tube(engine off)

thats all i can think of thats wrong with this car. but if i think of more i will post later.

here is a list of things ive done and how long ago they were done. *note - all this was done by me or my friend and I
-changed front brakes/rotors ~ 2 months
-changed struts/shocks ~ 2 weeks
-replaced PCV ~ 2 months
-changed air filter X2 ~ 1st time ~2.5 months /2nd time~4 days
-changed spark plugs X2 ~ 1st~bosch plats~2 months /2nd~NGK~3 weeks, were changed b/c boschs were white on electrode, and black on the threads
-checked MAF
-used auto diagnoise mode II to monitor fuel/air mixture, at idel CEL was flashing on/off at irregular intervals indicating toor lean/too rich respectivly, accerleration would show rich, and deceleration would show lean, i dont know if this is normal or not...
-check o2 sensor
-replaced o2 sensor~earlier today
-changed plugs/cap/rotor
-tightend throttle cable(no ot too much)
-checked all hoses, with the following results: leak is PS(resvior to pump) hose, not big however, leak in ATF cooler hose(not large, fluid level has not moved but it is greasy around it and after driving it is shiny)
-readjusted rear drums.
-adjusted idle to 800rpms in 'N', drops to ~700 in 'D' or 'R'
-listen to each injector pulse
- pulled plug wires 1 at a time, car stumbles on each one being pulled.
-Checked CV boots
-checked belt tension
-checked egr, with car off i was able to push it up, but it was a little hard
-checked and tightened/greased ALL suspension parts(control arm/strut to knuckle connector/tie rod/sway bar/ lateral link etc)

im tired of typing but there is more if you can help with any of this, PLEASE do im begging you.
thanks

EDIT: forgot to add i also(using the FSM) reset the fuel/air mixture learning data, first through the MAF, then through the o2 sensor. the MAF reset did make a difference but it went away the next day(back to normal)

psuLemon · Nov 14th, 2005, 08:21 AM

Quote:

Originally Posted by makaveli

2.steering feels "loose" all in your mind as our steering isn't that tight.

3.it seems to turn easier to the right side Right turns always seem easier on LHD cars. Its the nature of driving.

3(a). just had the wheels aligned, but it still pulls rights unless im taking turns fairly quick, then it seems to change the side it pulls to.Its prolly due to tire pressure/tire wear

3(b). front passenger wheel squeeks, only after the car has been drivin a while, and if i hit a bump some times it stopsdoes this happen all year round, cuz my do that noise in the winter with my suspension set up

3(c) during acceleration from a stop, the wheel rocks left to right(unless im holding it) check to see if your wheels are tightened.

4.sometimes there is a vibration from the rear(i think). this is strange, because it seems to vibrate the whole car.i think = all in your mind.

5.if i put it in neutral and rool backward the shit to reverse, there is a loud pop/click in the front end you should put it in gear while rolling, not good for tranny.

6.seems to hit bumps very hard, but struts/shocks were just changed you might be bottoming out. depending on bump size and speed it hits. in winter the suspension will be stiffer due to nature

7.at idle there is a loud hissing noise from the rear of the car, as well as the intake could have a leak in exhaust/ IM leak. Look for carbon build up.

8.brand new yokomo(sp?) 50,000 tires and worn down on the outer edges. i bought them about 6,000 miles/ 2.5 months ago. they're on the front and were put on because i was pulling into the parking lot at work, going about 15-20 MPH, and hit the front right tire on the curb and it popped, goodyear said it was too thin to repair.check tire pressure. uneven/too much/not enough will mess up your tires.

9.breaks make a groaning noise when stopping, not the whole time, but only right before i come to a complete stop. certain pads make noise, otherswise your rotors might be warped.

10. sometimes there is a lot of somke soming out the tail pipe, sometimes there is NONE. these happen at weird times too, sometimes it smokes after ive been driving like 1 hour and it sits at idle, sometimes it somkes when i start the car. but the strange thing is that when i start the car in the morning there is NO SMOKE coming out of the tail pipe. also when its not smoking, the sound from the exhaust sounds like the exhaust is Hallow/echoing, and is not very strong. when smoke is coming out, it sounds deeper like it is emminating from the tip of the exhaust, as opposed to somewhere inside the pipe, and it is also alot stronger.clean your egr system. all cars do smoke at times. also check your rear bumper to see if tehre is any soot

11.Excessive gas consumtion.due a tune up. also check fuel filter and check pulse rates of injectors.

12. at idle i hear a low rumble from the steering wheel, but it stops it i move the steering wheel at all(push it up/down, left/right, or in/out, not turn it)dont know

13. somthing(injectors?) under the hood is making a VERY loud clicking noise.an inector wont make clanking noise. if its like a grinding then it can be a tensioner problem

14. after driving for a while if i pull the engine oil dipstick out smoke starts to rise from the tube(engine off)we can the heat disapation (sp)

that should help you. No stop overthinking everything.

Powderfinger · Jun 13th, 2006, 06:39 PM

Makaveli...

I can't advise on all of your symptoms but the front end pulling to one side is almost always tire problems, especially since you say you just had it aligned....The front tires should always be a matched pair with the same level of wear. Equal tire pressure is crucial for having the car go straight down the road. If your front tires are not equal in every way, if one is worn on the edge and the other isn't then your car will pull to one side. Swap your front tires out with the rears (assuming they are evenly worn)....Put the two most evenly matched tires on the front. Ideally, if you can afford it, put a brand new matched set on the front end. You should be able to take your hand off the wheel on a straight-a-way and the car should stay put....If the front end is in align and your tires are equally worn and equally inflated, you will be able to do this....

As for the wheel rocking when you accelerate from a stop and the "noise" coming from the brakes (you say you just did the brakes so it's probably not brake related) I'd almost bet your CV joint(s) are shot....They can wear out and give out even if the boot hasn't broken....All the noise symptoms, pulling, grinding wobbling that you describe suggests CV joints....

Hopefully others can help with your other symptoms....Good luck man...