O2 Sensor Codes

As long as I have had my 996 (about 2 years) It will occasionally throw an upsteam O2 sensor code for bank 1 (1275 I think). Once it threw the other side. (1276), but only the one time. This would happen intermittently about 2-500 miles apart after I would clear the codes. Recently I finally got around to changing that bank 1 sensor with an original type Bosch sensor. Well right on cue it threw the 1276 code for the other side. Then a few hundred miles later it threw me a 1275 again for the same sensor I just changed. That is a bit annoying. Since I have 1 new sensor and 3 old ones doing math against each other is that throwing the whole system off? From experience are these likely to keep acting up until I replace all of them, or at least the other upstream sensor? For reference, I do have aftermarket exhaust behind the cats, but the cats appear stock. Car came from California and needed to pass emissions there so there isn't anything over radical.

I always change 02's as a a set.. At this point they could be 25 years old and their service life is typically 60 to 80K for best performance. YMMV!

Do the Downstream sensors do anything to affect engine management or are they just to confirm catalytic converter performance? Do they need to be replaced when replacing Upstream sensors?

When down stream sensors were introduced, they were strictly used for monitoring the efficiency of the cats. That was 30 years ago. Since then, modern ECUs use the front and rear sensor signals to estimate the efficiency as well as functioning temperature of the cats and that information is used in check engine light status. However, unless you get to talk to the Firmware engineer responsible for that piece of Porsche code, there is no way to be sure. In a Ferrari 458, for example, it will throw a Cat over temperature engine code and shut the offending bank of cylinders off, even though it does not have a thermal couple attached to the cat. Cool hah?

I am a federally licensed aircraft mechanic. I think I can handle changing the O2 sensor on the other side. I have considered the possibility of degraded cats, but because it's the pre-cat sensor code popping that seems unlikely. I already bought the other sensor because that was always the most likely scenario. I mostly posted because I was curious if the post-cat sensors functioned into the math for the pre-cat sensors, and I just wanted to see if there were similar common instances when people only change one sensor.

Post cat sensors r just there to confirm the cats work. They dont help or hurt the tune. U can graph the sensors with a decent scanner and u should be able to see a lazy sensor. It is not umcommon for these cars ti have o2 issues due to age.

What�s with all the chatGPT responses lately?

Quotes source post: 18855005

Is that what that was? I thought it was someone who just owned a really tall horse.

Quotes source post: 18854911

While ChatGPT is a powerful language model and can provide useful information on a wide range of topics, there are several reasons why relying on it to diagnose car trouble can be dangerous: Lack of physical inspection: ChatGPT operates solely based on text-based input and doesn't have the ability to physically inspect your vehicle. Diagnosing car trouble often requires hands-on inspection, checking for physical signs, and using specialized tools and equipment. Without these capabilities, ChatGPT may not be able to accurately identify the root cause of the problem. Limited context and information: When diagnosing car issues, it's important to provide detailed information about the symptoms, sounds, smells, and any other relevant details. However, ChatGPT may not always ask for or interpret the necessary details in the same way a trained automotive professional would. This can lead to incomplete or inaccurate assessments, potentially resulting in incorrect diagnoses and unnecessary repairs. Safety hazards: Misdiagnosing car trouble can have serious safety implications. A faulty diagnosis could lead to ineffective repairs or even exacerbate the issue, potentially putting you and others at risk while driving. Certain problems, such as brake failure or steering issues, require immediate attention from a qualified mechanic to ensure your safety on the road. Evolving automotive technology: The automotive industry is constantly evolving, with new models incorporating advanced technology and complex systems. ChatGPT's knowledge cutoff is in September 2021, meaning it may not be aware of the latest car models, diagnostic techniques, or software-related issues. Relying on outdated or incomplete information can lead to inaccurate diagnoses. Legal and financial consequences: Attempting to fix car issues based solely on ChatGPT's suggestions can have legal and financial implications. If you rely on inaccurate information and attempt repairs that result in further damage or violate warranty terms, it could void your warranty and lead to expensive repairs. Additionally, if you lack the necessary expertise, attempting complex repairs yourself can worsen the problem and create safety hazards. While ChatGPT can provide general guidance and information about car issues, it is always recommended to consult a qualified automotive professional or take your vehicle to a reputable mechanic for an accurate diagnosis and proper repairs.

Here is a question. Is there a timer to trip AGING SENSORS that only a PIWIS can fix? I have replaced all sensors and still get the code occasionally. There is nothing in Durametric to check age. The sensor is working according to live monitoring. When I purchased the car, there was rodent damage to the main harness I had to go to FSI to repair while they were rebuilding the engine. Since then, I have deleted the cats, installed an X pipe, and installed cute little cats for the down stream O2 sensors. So, should I set an appt with the dealer for first test resistance of my wiring repairs? I used silver solder and heat shrink for the repairs.

Quotes source posts: 18850002, 18855005

Exactly !! You never know how much "importance" the programmer puts on the particular information it can obtain until you have a lot of experience on the exact scenario..then you can see how much importance they actually placed on the information to change the results..and they call that "proprietary software".. Just last week I was called to testify as en "Expert Witness" in a VW case involving flaky intermittent software ...An Attorney was cross-examining me on my testimony about the software he mentioned how could I be so certain about their "proprietary software"? So I said well that is a whole other debate, I asked him, "If I buy that car, is that software mine or does it still belong to VW ??" ..lol...Case if it is mine I should have full access to know everything about it...lol John Deer was just ordered to make all their software available to Farmers to be able to "repair it themselves".. Its a new Act of Congress called "Right to Repair" .... I think it will filter over to Automobiles before too long... ChatGPT is dumber than a box of hammers, it keeps apologizing to me for giving me incorrect information ....lol...ask it some really tough questions that only you know the answer to ( really old school stuff) and see what it does...

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The simple aswere is no. The dme reads the values and yours r out of range. Which specific codes r u getting? It may just be that your small cats r not doing the job. Im my case an intermintent issue was from techs over the years probing the small pin at the dme and spredding the tabs enough that they would loose contact.

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That would be hard to find...

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It was many hours of diagnostics, jumper wires and dollars to test the dme. I To fix it, it only took $12 in parts ($11 was shipping) and 15min to depin and crimp new ends on. A magnifining glass is all it took to view the issue once i eliminated all the other possibilities.

FWIW , the "Aging" fault comes from the 02 sensor being too slow to switch states...from rich to lean or vice versa....When the DME gives a rich command to the injectors, it expects to see the 02Sensor react with a certain time-frame ( up to 3 seconds on early models) , if the 02 Sensor takes longer than this spec to react, the DME sets the "aging" code , meaning the 02sensor is slow to respond but is responding... Slow responding 02 Sensors can waist a lot of fuel even if they are not yet setting an "aging " code...