P2096 Porsche fault code 16 - Oxygen sensor ageing Delay bank 1

[Silver_TT]

2002 C4S (US)

I was driving today and got a CEL. Got home and hooked up the Durametric and got the following error:

P2096Porsche fault code 16 - Oxygen sensor ageing Delay bank 1

Loren, I found this archived post in which you were very helpful:

http://www.renntech.org/forums/topic/13925-cel-error-code-p2096/

First, I have cleared the code and will monitor to see if this comes back in the future. Just thinking ahead here though because my car does have 100K miles on it, If I understand you correctly, this error above is for the post-cat oxygen sensor, correct? Is there good reason to replace the pre-cat sensor at the same time?

Also, I know bank 1 is on the drivers side. Loren, in the post above you advocated cleaning the contacts after clearing the code. I was just wondering how accessible this sensor is and what the recommended method of cleaning the contacts was.

Thanks very much in advance.

[JFP in PA]

You can clean the electrical connections with any commerical electical connector cleaning spray from someone like CRC, you could also use their MAF sensor cleaner as well.

The O2 sensor is not that hard to get at, but it is in a bit of a confined space so don't rush it. Put a dab of antiseize on the threads of the new one, and make sure it is properly tightened (they are known to come loose). A decent O2 sensor wrench is also a good investment.

[Silver_TT]

Thanks for the response, JFP.

Is the Durametric saying that the oxygen sensor part that's throwing an error is part # 996.618.660.15 (see screenshot from my post above)? This is what it shows for "Part Number" in the Durametric screenshot... but I show part # 99660616801 for the pre-cat and 99660617801 for the post cat.

2/27/13 UPDATE/CORRECTION: The Durametric is just identifying my Motronic 7.8 DME as part # 996.618.660.15 -- it's not attempting to identify the part # of the oxygen sensor that's throwing the error (see above). In other words, I was mistaken in my interpretation. Identifying the part # of the part that's throwing an error would be a cool feature maybe for the future, but is not what the Durametric is attempting to do here.

Edited December 29, 2023 by Silver_TT

[JFP in PA]

Not surprising, the O2 sensors have been updated more than once, so they often have new part numbers. Check with a dealer like Sunset to get the latest number.

[Silver_TT]

Thanks a bunch. Last but not least, can you confirm that this error code is referring to the post-cat sensor not the pre-cat sensor or both (I believe Loren implied it was the post-cat in the post I referenced). In this scenario is it recommended to replace the post-cat sensor only? Or do shops normally do them in pairs (pre + post)? I don't normally fix what isn't broke...but 100K miles on my vehicle.

Edited December 29, 2023 by Silver_TT

[Loren]

P2096 Signal Delay Time for Oxygen Sensor Ageing - Above Limit

Sorry this could be either sensor as the test measures the delay between them. The two sensors are different so do not interchange them.

[Silver_TT]

Ahh ok, thanks Loren, that's an important clarification. If I do a replacement I will replace both the pre-cat and the post-cat sensors on Bank 1.

For now I have cleared the code and will see if it comes back.

Thanks to both of you for the information.

[JFP in PA]

Thanks a bunch. Last but not least, can you confirm that this error code is referring to the post-cat sensor not the pre-cat sensory or both (I believe Loren implied it was the post-cat in the post I referenced). In this scenario is it recommended to replace the post-cat sensor only? Or do shops normally do them in pairs (pre + post)? I don't normally fix what isn't broke...but 100K miles on my vehicle.

The sensors can be tested individually as they are simple electrical devices that operate is certain voltage ranges. As the code indicates that the timing of the signal between the two sensors on that bank are out of range, it could be only one, or it could be both (most of the time, it is the one after the cat). Usually we test both sensors to see which is not up to snuff as these things are not cheap. Unfortunately, I am away from my shop at the moment, so I do not have the testing voltages at hand, perhaps Loren may have access to them.

[Loren]

The easiest way to test the sensors (IMHO) is by comparing the O2 sensor graphs in Durametric (or PST2, or PIWIS).

[Silver_TT]

Thanks, JFP. That's really good information, can't thank you guys enough. Ya, I believe the Durametric can monitor these voltages.

Since these sensors are 100K miles old, I will keep my eye on the fault codes. If this re-appears I will just go ahead and replace both the pre and the post. They are only $150 a piece or so for the Bosch.

[JFP in PA]

The easiest way to test the sensors (IMHO) is by comparing the O2 sensor graphs in Durametric (or PST2, or PIWIS).

True enough, but it can also be done with a simple multimeter if one does not have access to one of those; if memory serves, I think the voltages on a good sensor are 450mV between pins 3 and 4, and 720mV between pin 3 and ground.

[Silver_TT]

JFP & Loren,

Everything was fine the last 2-3 weeks but today the CEL came on again and when I got home tonight and hooked up the Durametric it's showing (see attached):

P0420

Porsche fault code 40 - Cat. conv efficiency bank 1

P0430

Porsche fault code 45 - Cat. conv efficiency bank 2

So the original error message did not reappear but now I'm getting these two. Weird since I wouldn't expect to all of a sudden have problems with the cats on BOTH Bank 1 & Bank 2 simultaneously when everything has all been fine up to this point.

I had ordered the pre-cat and post-cat oxygen sensors (1 of each) which I had planned to install on Bank 1 here shortly. Should I continue with this? I read these oxygen sensors are good for about 100K miles and I just rolled over that a month ago or so.

How should I proceed in troubleshooting at this point?

As always, your expertise and guidance is greatly apprecaited.

Edited December 29, 2023 by Silver_TT

[Ahsai]

The way I look at it is @100k, you've got your money worth of the original sensors anyway. I would just replace both sensors in bank 1, erase those codes, and keep monitoring. This will help further diagnosis by eliminating those sensors in bank 1.

If same cat code comes back on both sides, you can then look else where at something common upstream. If no more codes from bank 1, at least you've fixed that side.

[Silver_TT]

I'm OK with it if this is just means a replacement of the 4 sensors but it seems too coincidental that Bank 2 is now throwing faults. In other words, what are the odds of Bank 1 and Bank 2 both independently crapping out at once? As Ahsai said, it makes me wonder if there's something else going on further upstream. Just seems weird that Bank 1 and Bank 2 would both start to show problems at the same time. I've seen other posts about this same problem on RennList and 6speed, but unfortunately those posters never never followed up on their threads as to what the conclusion was so all I know is that someone else has had this same problem in the past.

I'm a little bit worried because I don't want to damage the cats while I drive around clearing codes trying to figure out what's going on if there really is a problem and it's not just the sensors. Making matters worse, I have a number of track events coming up in April that I can't afford to attend with the car at less than 100%.

[Ahsai]

You can log the o2 sensor voltages on all 4 sensors (with durametric or even a generic obdii scanner) On both banks. After engine warm up, at idle, precat sensors should swing between 0.2-0.8v once a second. Post cat sensors should read about 0.7v almost steady. If you see the post cat reading kind of following the precat readings, your cats are shot.

Now repeat the above but drive the car around. The pre cat should swing about 10 times a second when the post cat will still be around 0.7v most of the time. If you accelerate, both pre and post cat reading will hit 1v almost instantly When you let off the gas quikly, both reading will go to 0 almost instantly.

Edited February 23, 2013 by Ahsai

[JFP in PA]

JFP & Loren,

Everything was fine the last 2-3 weeks but today the CEL came on again and when I got home tonight and hooked up the Durametric it's showing (see attached):

P0420

Porsche fault code 40 - Cat. conv efficiency bank 1

P0430

Porsche fault code 45 - Cat. conv efficiency bank 2

So the original error message did not reappear but now I'm getting these two. Weird since I wouldn't expect to all of a sudden have problems with the cats on BOTH Bank 1 & Bank 2 simultaneously when everything has all been fine up to this point.

I had ordered the pre-cat and post-cat oxygen sensors (1 of each) which I had planned to install on Bank 1 here shortly. Should I continue with this? I read these oxygen sensors are good for about 100K miles and I just rolled over that a month ago or so.

How should I proceed in troubleshooting at this point?

As always, your expertise and guidance is greatly apprecaited.

This is a situation where you need to walk a fine line; P0420 and 0430 are the indication of a three way cat problem, but with one massive caveat: If an aged oxygen sensor is coded along with the cat fault, the OEM diagnostic manual recommends retesting with a new sensor to see if the cat fault returns. The reason for this is the aging sensor(s) can give the false indication of a dying cat when there is really nothing wrong with it. And the three ways are very expensive. Previously, you threw a P2096 (Signal Delay Time for Oxygen Sensor Ageing - Above Limit), which indicates one, or both, sensors are slow in responding ("aging"), which makes your situation a "poster child" for looking at the O2 sensors before even thinking about the three way cats.

Connect the Durametric and test both sides front and rear O2 sensors to see if they are active and "in bounds" in responding.

[JFP in PA]

I'm OK with it if this is just means a replacement of the 4 sensors but it seems too coincidental that Bank 2 is now throwing faults. In other words, what are the odds of Bank 1 and Bank 2 both independently crapping out at once? As Ahsai said, it makes me wonder if there's something else going on further upstream. Just seems weird that Bank 1 and Bank 2 would both start to show problems at the same time. I've seen other posts about this same problem on RennList and 6speed, but unfortunately those posters never never followed up on their threads as to what the conclusion was so all I know is that someone else has had this same problem in the past.

I'm a little bit worried because I don't want to damage the cats while I drive around clearing codes trying to figure out what's going on if there really is a problem and it's not just the sensors. Making matters worse, I have a number of track events coming up in April that I can't afford to attend with the car at less than 100%.

Sometimes a load of questionable quality fuel can annoy the sensors, and many times the damage is permanent (fouling). You need to retest the sensors to see where you are.

[Silver_TT]

On 2/22/2013 at 11:34 PM, Ahsai said:

You can log the o2 sensor voltages on all 4 sensors (with durametric or even a generic obdii scanner) On both banks. After engine warm up, at idle, precat sensors should swing between 0.2-0.8v once a second. Post cat sensors should read about 0.7v almost steady. If you see the post cat reading kind of following the precat readings, your cats are shot.Now repeat the above but drive the car around. The pre cat should swing about 10 times a second when the post cat will still be around 0.7v most of the time. If you accelerate, both pre and post cat reading will hit 1v almost instantly When you let off the gas quikly, both reading will go to 0 almost instantly.

See attached for part of the log I captured from the Durametric (I wanted to upload the whole .csv file but it doesn't look like it's supported). This was captured with the car running and ideling (after the engine was pretty warm).

Please correct me if I'm wrong or someone chime in please to check my math: Pre-cats look ok on Bank 1 & 2 but Post-cats data on both banks does not look good. Post-cat readings seems to be following the pre-cats from what I can see. Based on what Ahsai was saying, the cats could be bad. Seems too coincidental that both cats would fail at once so I'm still planning to replace both pre and post cat o2 sensors on both Bank 1 & 2. Everyone agree?

One other question I had was with respect to the following. Why isn't the car's computer throwing a CEL now? If the post-cats are bad based on this data, why isn't it triggering a CEL? Since I cleared the errors yesterday evening I've done quite a bit of driving both at low RPMs and at high RPMs, and no CELs have been triggered. Seems like I should be getting a CEL if the post-cat sensors are bad based on this data??

Edited December 29, 2023 by Silver_TT

[JFP in PA]

Main cat failures are not a common event, but they do happen. That said, I would be suspicious of both going south at the same time; that would be a very rare event.

You could also do the same test as a road test per the suggestion, and see how the sensors respond to large scale throttle and exhaust volume changes.

O2 and cat related codes are not instantaneous, they require cumulative "cycles" with out of bounds values to kick a code, otherwise the car would be throwing a code just about every time you drive it.

As mentioned earlier, you have previously thrown an "aging" sensor code, which needs to be evaluated (trying a new sensors on at least one bank) before considering jumping for the cats. Cars with failing cat also often have exhausts that stink because of the failing cats. The three way cats are going to retail around $2K each, sensors look like a bargain by comparison............

[Silver_TT]

Thanks JFP and Ahsai. Your guidance has been incredibly helpful.

Since I couldn't upload the log and RennTech only allows images, I also attached two graphs I created in Excel using the Durametric data and showing the pre and post cat sensors on Bank 1 and Bank2. You can see that it appears the post-cats are following the pre-cats.

I will definitely replace the o2 sensors first before even thinking about the cats. Based on what I see here, maybe I only need to replace the post-cats as a first step? It looks like the pre-cats may be ok?? JFP, I saw you said earlier that usually when these sensors go out, it's more often the post-cat.

One last question: What would the exhaust stink like if the cats were bad? Would it just have a strong smell of fuel ?

Edited December 29, 2023 by Silver_TT

[JFP in PA]

Yes, the post three way seem to die first.

When the cats die, you often get a rotten type smell, sometimes like rotten eggs, because the unit is not doing the chemcial conversion it is there to do.

An addtional thought, if you have a service station near by that does state emissions inspection, ask them if they have a "sniffer", which is a probe that is inserted into the exhaust to measure the gas mixture being emitted (hydrocarbons (HC) in parts per million (ppm), CO2 in percent, and the carbon monoxide (CO) in percent). Some also do NOx. If they do, have them test your car after it is fully warmed up (take it for a ride), you should see something to the tune of 200 PPM or less hydrocarbon, <500 PPM for NOx, and around 0.02 to 0.03% CO; if you do, the cats are fine, it is the sensors.

[Ahsai]

Sorry to say but from your readings, it does look like your cats are shot. Healthy O2 readings should be like those in post #4 (after 44:15 in post #4) and #5 here

http://www.renntech.org/forums/topic/37019-p0491-p0492-o2-problem/

Another thread here posts #1 and #5 here http://www.6speedonline.com/forums/996/163011-what-does-dead-catalytic-converter-looks-like.html

Since the cats are very expensive, I would still suggest installing your new precat and postcar sensors on bank 1 and do the log again. If you see no diff in your readings, it's very likely the cats are shot. However, if you see bank 1 reading back to normal, you can then install new sensors on bank 2 to fix it as well. Makes sense?

Now that I see you're tracking your car, it's not difficult to kill the cats due to more time spent on WOT, where the DME will go OPEN loop and give enriched mixture...

Edited February 23, 2013 by Ahsai

[Silver_TT]

Don't bet against my cats yet. The exhaust does not smell bad at all. On a cold start the post-cat sensors were behaving normally for 15 or 30 seconds or so before they started going haywire. I will replace those sensors and report back with the results.

JFP, Thanks for the suggestion on emmissions--I will do this some time this week.

[Ahsai]

I do hope it's just the sensors (hence my suggestion of replacing them first) and i hope you don't take me wrong. I assume you saw a steady voltage on the post-cat briefly after cold start. That is normal because the postcat sensors are not heated up to their operating temperature yet during that time.

[Silver_TT]

No worries, I definitely appreciate the input so thanks. Will report back later this week when the sensors come and I can do the install (I ordered all 4 but will start with the Bank 1 post-cat first and then log with Durametric again to see if I can observe that constant-like voltage I want to see after the cat).

Fingers crossed it's the sensors not the cat$. Either way, I have to say, it does seem very coincidental that both sensors or both cats went at the same time. As JFP said, it could have been something like fouling with bad gas that smoked both of my sensors -- I'm hoping it's not something bigger that's just manifesting itself downstream by damaging my exhaust system.

Thanks for your guys' help!

Stay tuned . . .