o2 sensor failure help

[dave1964]

Hi all,

I have a 2001 VX LS1 with 220 k on the clock. Had it for a few years now and it had a 2 1/2" cat back exhaust on it when i got it. It has done 3 o2 sensors in the last 3 months all in the left bank. Using genuine sensors so need to fix problem as they are not cheap. I have had a ScangaugeII connected during this time. When first sensor went it showed on scangauge. O2 reading was abnormal and fuel trim was maxed out postive (rich) meaning sensor was giving a lean reading. Changed sensors over and readings changed bank meaning sensor had failed, but why. Since done 2 sensors in same bank. when new sensor is fitted Scangauge readings are the same for both banks, o2 and fuel trim. Then after a month or so the sensor fails again. Have checked for air leaks, doesn't appear to be using coolant. Ran local Holden dealer hoping to speak tp experienced mechanic. He came back with air leak, check pcv etc. Pcv goes into manifold so would effect both banks, so this tells me he didn't understand what he was being told. Scangauge tells me no leak, as I would have thought it would show. I'm thinking contamination. Any "very" experienced people out there that can help? I thought this would be a common problem and easily diagnosed. Maybe not.
Any help appreciated. TIA

Dave

[RIDE:42]

get them turned off end of problem

[dave1964]

didn't know you could, better to find and fix problem i feel

anyway, i consider it economical for a 350 V8 and would like to keep it that way.

I askede holden dealer about oil contamination and he said not likely. I just read on this forum that oil contamination is an issue with gen3's??????????

plugs 4 & 3, on left of picture show signs of using oil, 2 & 1 look dry.
no pic, don't know how to upload to this forum

[VX2VESS]

Hi all,

I have a 2001 VX LS1 with 220 k on the clock. Had it for a few years now and it had a 2 1/2" cat back exhaust on it when i got it. It has done 3 o2 sensors in the last 3 months all in the left bank. Using genuine sensors so need to fix problem as they are not cheap. I have had a ScangaugeII connected during this time. When first sensor went it showed on scangauge. O2 reading was abnormal and fuel trim was maxed out postive (rich) meaning sensor was giving a lean reading. Changed sensors over and readings changed bank meaning sensor had failed, but why. Since done 2 sensors in same bank. when new sensor is fitted Scangauge readings are the same for both banks, o2 and fuel trim. Then after a month or so the sensor fails again. Have checked for air leaks, doesn't appear to be using coolant. Ran local Holden dealer hoping to speak tp experienced mechanic. He came back with air leak, check pcv etc. Pcv goes into manifold so would effect both banks, so this tells me he didn't understand what he was being told. Scangauge tells me no leak, as I would have thought it would show. I'm thinking contamination. Any "very" experienced people out there that can help? I thought this would be a common problem and easily diagnosed. Maybe not.
Any help appreciated. TIA

Dave

thats your problem factory sensors with a system etc, get the bosch ones from repco etc they last heaps longer on the early ls1's. do a search on here used to be a whole thread on them

here http://www.ls1.com.au/forum/showthread.php?t=44963&highlight=bosch&page=2

[macca_779]

Turn them off. If the tune is good they won't be doing anything anyway.

[dave1964]

[quote=vt2vx;1902844]thats your problem factory sensors with a system etc, get the bosch ones from repco etc they last heaps longer on the early ls1's. do a search on here used to be a whole thread on them


doesn't make sense. the original sensors have last for years with the exhaust system that is fitted (2 1/2 cat back) why would it suddenly start doing sensors on left bank only???

[dave1964]

I think experienced mechanics are a thing of the past. Fingers in to many pies and rely to much on computers for diagnosis.

[dave1964]

ok, having read that the sensors can be cleaned i thought this an option till the issue is sorted. Well i can tell you from my own experience this is a load of rubbish, and no, not even lemon juice works.

I have come to the conclusion that it is oil contamination and would have thought this a common problem on higher milage ls1, therefore a known problem and easily diagnosed. Apparently not.

So next question is where is the switch to turn o2 sensors off? :lol:

Seriously though, to turn them off until i get engine ringed is probably only option at this time. What is the process and who can do it?

TIA

Dave

[boggers007]

ok, having read that the sensors can be cleaned i thought this an option till the issue is sorted. Well i can tell you from my own experience this is a load of rubbish, and no, not even lemon juice works.

I have come to the conclusion that it is oil contamination and would have thought this a common problem on higher milage ls1, therefore a known problem and easily diagnosed. Apparently not.

So next question is where is the switch to turn o2 sensors off? :lol:

Seriously though, to turn them off until i get engine ringed is probably only option at this time. What is the process and who can do it?

TIA

Dave

Someone with EFI live and possibly HP Tuners? basically a tuner who knows what they are doing providing the tune is good.

[dave1964]

Thanks.

Everything has its pros and cons. what are the downside of turning them off?

When all is in order fuel trims are always around zero, does this mean the tune would be "good".

A side note. I had the pcv go a while back and whilst it threw a lean code it did not damage sensor. So the local holden expert has no idea.

[Toddler78]

A side note. I had the pcv go a while back and whilst it threw a lean code it did not damage sensor. So the local holden expert has no idea.

dont jump to conclusions, he has some idea. a air leak (unmetered air getting into engine) has been known and is common for throwing o2 sensor faults. its not damaging the sensor but the sensor is picking up a lean reading because of the air leak. However you are right in saying he had misdigagnosed it as if it was a PCV leak, swapping out o2 sensors would not have rectified the issue as in your case it obviously had for a period of time.

[dave1964]

dont jump to conclusions, he has some idea. a air leak (unmetered air getting into engine) has been known and is common for throwing o2 sensor faults. its not damaging the sensor but the sensor is picking up a lean reading because of the air leak. However you are right in saying he had misdigagnosed it as if it was a PCV leak, swapping out o2 sensors would not have rectified the issue as in your case it obviously had for a period of time.



holden expert was told it was "destroying" the sensors, and all in left bank, so wrong call

[peter b]

Thanks.

Everything has its pros and cons. what are the downside of turning them off?

When all is in order fuel trims are always around zero, does this mean the tune would be "good".

A side note. I had the pcv go a while back and whilst it threw a lean code it did not damage sensor. So the local holden expert has no idea.

Have you actually left it with a mechanic to have the problem rectified or are you just making claims as to what you think he does or doesn't know based on what info you give him.
Any answer you are given is going to be incorrect as all people have to go on is what you say. Before you lay claims that experienced mechanics are a thing of the past how about leaving your car with a mechanic to have the problem rectified as you seem to be just intent on throwing sensors at it hoping it will fix itself.

[dave1964]

pcv was entirely seperate incident and correctly diagnosed by holden mechanic in another town

[dave1964]

Have you actually left it with a mechanic to have the problem rectified or are you just making claims as to what you think he does or doesn't know based on what info you give him.
Any answer you are given is going to be incorrect as all people have to go on is what you say. Before you lay claims that experienced mechanics are a thing of the past how about leaving your car with a mechanic to have the problem rectified as you seem to be just intent on throwing sensors at it hoping it will fix itself.

give me break, another who can't read and has no idea

[peter b]

give me break, another who can't read and has no idea

I can read and if you think I have no idea I would rethink your comment mate I am not simply someone who will make a claim without backing it up. If you had said they looked at your car and got it wrong no problem but with what your making claims of this proves to be lot of claims because he can't give you this is 100% your problem. Give you a tip an electrical/mechanical fault like this is hard to prove without actually having the car. Little bits of info go nowhere yes you have been through sensors on that side only ok but obviously the sensor is and always was the SYMPTOM not the fault. Fixing a symptom is a bandaid fix
People who make claims like this is a big reason I got out of the trade they love you when you can give them a definate answer so they can then fix it themself but when it is something that could be 1 of many all of a sudden we don't know what we are on about.

[VX2VESS]

[quote=vt2vx;1902844]thats your problem factory sensors with a system etc, get the bosch ones from repco etc they last heaps longer on the early ls1's. do a search on here used to be a whole thread on them


doesn't make sense. the original sensors have last for years with the exhaust system that is fitted (2 1/2 cat back) why would it suddenly start doing sensors on left bank only???

Must be a reason. only know i went through a number of factory O2's, then change to Bosch and had no more issue with short life.

[dave1964]

vt2vx

i hear ya. will take that on board.

to others

local dealer was told everything he needed to know. if there was a dealer where i live i would have already taken car in

yeah, i'm posting here because i think there's nothing wrong or i think it will fix itself

a sensor is an electrical device and will fail due to no other cause, as it turns out this is not the case here

just so happens one of my older brothers is a qualified mechanic, living in UK at the moment unfortunately.

i will only reply to constructive critasism from this point

[dave1964]

don't forget i tried to upload pic of #4 plug, bit oily

[peter b]

The point still remains that this really isn't something that can easily be diagnosed with out the car. Problem is the mechanics comments are correct for what is common as air leaks do cause the codes and have seen some weird things happen. The sensor can fail on its on with no other cause yes but here there is something causing it to fail.
You may think you are giving him all he needs to know but still he can't test anything. I can tell you it is xxx part but the thing is without proving it any answer you get is wrong. Changing to a different brand of sensor still won't help as I don't believe it is a sensor issue whether it be your car is using heaps of oil to the point that you would be seeing smoke out the back and on the dipstick. After an oil change do 2500ks then recheck your dipstick should give an idea of how much it is using.
The sensors are a common failure but not that common where they only last a short period of time.
Another issue is on the left side is where the drain hole for the A/C is check the plug on both the O2 sensor side and the wiring harness side and look for signs of rust on the terminals.
The o2 going darker one side to the other doesn't really show that there is a big fault as often they are different colour to each other.
Failing that check the wiring harness for a break or bad connection

[dave1964]

I have been tinkering with all things mechanical and electrical all my life, i do understand that more offen than not it is difficult to diagnose a problem without seeing it. As I already said " i "thought" this one could be easily diagnosed, apparently not". And don't worry, I have have seen my share of weird stuff.

Car uses little oil, no smoke, can see #4 cylinder is a bit oily.

Have already checked sensor connections, cleaned them again with contact cleaner this morning (were'nt dirty or rusty) when i tried cleaning sensor

Will check harness but not likely the problem, runs without fault, then fails, and stays failed. Put a new sensor in, same thing

thanks

Dave

[dave1964]

harness doesn't make sense either because sensor doesn't work in other side

[peter b]

I have seen intermittant wiring faults before where it isn't quite a break but isn't good connection at times that why i said check the harness. It is basically separate to the other side. For the amount of oil you are using I wouldn't think oil contamination being an issue as it would have already burnt before it reaches the sensor. Some electrical faults are quite easy but when it is something that works fine for a short period and fails repeatedly it gets quite compliated. This is why I say the info alone won't give you the result you want I am going to recommend you take it to your local dealer and ask for the foreman to look at it generally the foreman is the most switched on and can work out the issue for you. Doing this way will give you differing answers with a lot of people saying turn them off.

[dave1964]

I hear you peter.

But if you have followed what I have said the statement is true "it is not logical that it is wiring".

Not saying it is not or can't be, I'm saying it is not logical.

Whilst at this time i am leaning towards oil contamination there is something telling me otherwise. That is, there are many old (vn vp)high milage commdores out there that run o2 sensors that must be using alot of oil, and are not doing sensors. Or if they were we would know and this would be easily diagnosed. Of course the vn vx sensors are different, later has heater for example.

How much help one gets from a mechanic largely depends on the individual and even where you live to a degree. I could give you some stories of people here being charged huge amounts of money ($2400 seen receipt and car) and get car back without problem being fixed. I have been bitten myself, fortunately not that much money was involved.

I just read post where a bloke had very similar problem to me. He had a commodore he had owned for 3 years, had same exhaust system on it during this time. Started throwing sensors all of a sudden. Took it to holden dealer, they told him sensor had failed and replaced it. Sure enough, it failed again in short order. He took it back, they then claim its his exhaust. He said this does not make sense exhaust has been on there for years with no issue. Thread ended there.

If all else fails, and before I tear motor apart, I will take your advice and see foreman at local (nearest) holden dealer.

thanks

Dave

[dave1964]

More often than not logic holds true, but when you the weird problems all logic goes out the window.

[Toddler78]

I will throw this one out there, check to see if your cat hasnt become blocked or colapsed, if it is causing a restriction in the pipe work then it may be creating enough heat to cause the sensors to fail.

[klink]

I hear you peter.

But if you have followed what I have said the statement is true "it is not logical that it is wiring".

Not saying it is not or can't be, I'm saying it is not logical.

Whilst at this time i am leaning towards oil contamination there is something telling me otherwise. That is, there are many old (vn vp)high milage commdores out there that run o2 sensors that must be using alot of oil, and are not doing sensors. Or if they were we would know and this would be easily diagnosed. Of course the vn vx sensors are different, later has heater for example.

How much help one gets from a mechanic largely depends on the individual and even where you live to a degree. I could give you some stories of people here being charged huge amounts of money ($2400 seen receipt and car) and get car back without problem being fixed. I have been bitten myself, fortunately not that much money was involved.

I just read post where a bloke had very similar problem to me. He had a commodore he had owned for 3 years, had same exhaust system on it during this time. Started throwing sensors all of a sudden. Took it to holden dealer, they told him sensor had failed and replaced it. Sure enough, it failed again in short order. He took it back, they then claim its his exhaust. He said this does not make sense exhaust has been on there for years with no issue. Thread ended there.

If all else fails, and before I tear motor apart, I will take your advice and see foreman at local (nearest) holden dealer.

thanks

Dave

does your scan guage give you the voltage fluctuations of the sensor as when you look on some scan tools you see the rapid change in voltage. so with this in mind it could be like stated above a wiring problem.

have you looked at your air filter to see if that is clean as that can effect fuel usage and you may have an injector pumping to much or to little fuel in #4 and the oily film may be fuel and carbon.

Also check how clean your throttle body is as the pcv valve up by the throttle bottle might be stuffed

[ebbett21]

I went sensors like you a while back, and in the end the tuner stuck in a higher Ohm ones and they work fine now, the factory spec ones wernt up to the flow.

[SirNemesis]

I spent way too long chasing o2 sensor / loom problems with my car. I don't bother running them at all anymore, disabled in the tune. If you tuner knows what he is doing you won't need them.

[dave1964]

I will throw this one out there, check to see if your cat hasnt become blocked or colapsed, if it is causing a restriction in the pipe work then it may be creating enough heat to cause the sensors to fail.


Definately will check that one thanks

[dave1964]

does your scan guage give you the voltage fluctuations of the sensor as when you look on some scan tools you see the rapid change in voltage. so with this in mind it could be like stated above a wiring problem.

have you looked at your air filter to see if that is clean as that can effect fuel usage and you may have an injector pumping to much or to little fuel in #4 and the oily film may be fuel and carbon.

Also check how clean your throttle body is as the pcv valve up by the throttle bottle might be stuffed


yes scangauge shows voltage, has 4 displays so i can watch both banks at same time. o2 voltage and fuel trim both banks for example.

Throttle body etc all done by holden dealer not so long ago.

Always look after filter, averaging around 9.5 liters/100km

[dave1964]

does your scan guage give you the voltage fluctuations of the sensor as when you look on some scan tools you see the rapid change in voltage. so with this in mind it could be like stated above a wiring problem.

have you looked at your air filter to see if that is clean as that can effect fuel usage and you may have an injector pumping to much or to little fuel in #4 and the oily film may be fuel and carbon.

Also check how clean your throttle body is as the pcv valve up by the throttle bottle might be stuffed


yes scangauge shows voltage, has 4 displays so i can watch both banks at same time. o2 voltage and fuel trim both banks for example.

Throttle body etc all done by holden dealer not so long ago.

Always look after filter, averaging around 9.5 liters/100km

[dave1964]

Also have scantool now. Just read DTC's, only 1 there, 0131, left bank lean

faulty sensor will give this, does not necessarily mean left bank is lean

scangauge won't do dtcs but told me same thing

[dave1964]

I went sensors like you a while back, and in the end the tuner stuck in a higher Ohm ones and they work fine now, the factory spec ones wernt up to the flow.

very interesting to hear, thanks

[ratter]

Cleaning the o2 sensor connections with contact cleaner can kill the sensor, don't ask me how I found that one out.
O2's will die with age.
O2's will die with contamination

[dave1964]

Cleaning the o2 sensor connections with contact cleaner can kill the sensor

with all respect, i find that one hard if not imposible to believe

the cleaner does not touch sensor???????????

dave

[dave1964]

cleaning "sensor" with contact cleaner may very well damage it.

a mate just pointed something out to me.

An o2 sensor is a thimble shaped zirconia ceramic, with a thin layer of platinum on each side. One side (outside) reading oxygen in exhaust other (inside) reading oxygen in outside air. So there is a port on sensor linking outside air to one of the platinum layers (inside layer). What this means is the sensor can be contaminated from the outside by water oil etc.

I do have a crank rear seal leak, and i know oil is getting on outside of left sensor. Could this be it???

There was mention on one of the engine management forums or something of bosch sensors being "tougher".

Also on bosch website it mentions something about their sensors being submersible, sealed to prevent premature failure due to water splash and contamination. Maybe they port outside air through lead???

[dave1964]

Update on my last post

Had i good look at a sensor this morning, certainly no visible sighs of a port or vent of any kind.

No oil on outside of last failed sensor yet.

Looking more and more like this is one of those weird issues no one has an answer to, including me.

[Dreamer]

Does the code always get logged under the same conditions each time, or does it get logged and then cant be cleared (ie comes back as soon as you clear it or does it just come back after you drive x distance ect)

[dave1964]

not exactly sure what you mean, but it comes on about 5-10 km of driving

out of curiosity i put a temp gun over exhaust, pipes same temp cats forward,
left colder after cat. will have to check a few more times to confirm this.

[peter b]

I hear you peter.

But if you have followed what I have said the statement is true "it is not logical that it is wiring".

Not saying it is not or can't be, I'm saying it is not logical.

Whilst at this time i am leaning towards oil contamination there is something telling me otherwise. That is, there are many old (vn vp)high milage commdores out there that run o2 sensors that must be using alot of oil, and are not doing sensors. Or if they were we would know and this would be easily diagnosed. Of course the vn vx sensors are different, later has heater for example.

How much help one gets from a mechanic largely depends on the individual and even where you live to a degree. I could give you some stories of people here being charged huge amounts of money ($2400 seen receipt and car) and get car back without problem being fixed. I have been bitten myself, fortunately not that much money was involved.

I just read post where a bloke had very similar problem to me. He had a commodore he had owned for 3 years, had same exhaust system on it during this time. Started throwing sensors all of a sudden. Took it to holden dealer, they told him sensor had failed and replaced it. Sure enough, it failed again in short order. He took it back, they then claim its his exhaust. He said this does not make sense exhaust has been on there for years with no issue. Thread ended there.

If all else fails, and before I tear motor apart, I will take your advice and see foreman at local (nearest) holden dealer.

thanks

Dave

Dave
Everytime I have had a repetitive issue like this logic doesn't always show the fault. Still have to treat the sensor as a symptom at this stage because yes they die but not that quickly. Oil contamination doesn't hold up especially considering only one spark plug was a little oily. Yes you can get the fault to move with the sensor. But the reason I said check the harness as when plugging in and unplugging connectors in turn you move the wiring and have seen some really strange things that happen. Heres an example VS commodore comes in left hand hi beam works but drivers side doesn't is it the globe the wiring or the fuse?? Seen lots of people get caught out and change the globe and then come ask why it isn't fixed. In this case most times it is the fuse.
Logic tells you it is a sensor and that would be true too if it only failed once. I still stand by this is a fault that needs to be thoroughly checked. Checking resistance in the harness. Checking the O2 sensor harness itself. When you pull it out do you disconnect it first or wind it in with the plug connected??
If so the problem may well be how they are being installed ( I am not making claim that is how you fit it by any means but none the less if that is how they are being fitted and removed this will damage the wiring on the sensor side of the plug)
Yes there might well be a simple answer but the trouble is finding it

Hope by now you have it sorted