18 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHMy 200 cell cats finally threw a code
Reported repair
Replace maf and no more code
Reported resolution
1
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0
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1
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Read evidence and context
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Discussions that report a fix
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Leading evidence: 'Replace maf and no more code' (1 discussions report resolution; 0 report an unsuccessful attempt). Across 1 matching discussions, the most frequently mentioned possible cause is 'mass air flow sensor' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Replace maf and no more code' (1 discussions). For that action, 1 discussions report a resolution and 0 report an unsuccessful attempt. The most frequently reported fix is 'Replace maf and no more code', supported by resolution reports in 1 discussions. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Performed · outcome unconfirmed · Original poster
I thought it only adjusted based on the upstream 02 sensor but I don't know for sure
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Performed · outcome unconfirmed
Anyway I cleaned the maf with CRC, great, the car even runs better.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed
So I replaced the MAF and all three codes went away.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
18 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 1 adjusted by outcome qualification.
2 acknowledgements have no verified action link; they do not establish a repair result.
Outcome without a verified action link
Very easy installation - surely even easier on the 996 - and no more code.
I expected this and I don't really like the sound anyway so I'm thinking about installing my stock cats and getting a set of mufflers...but is there something else I can do with software to eliminate the code and eliminate the throttle delay at the same time?
Check your MAF sensor. I have 200-cell cats on a 986.2 Boxster (basically same motor, just smaller). When I got a recurring code, after doing a little homework I picked up a new MAF. Very easy installation - surely even easier on the 996 - and no more code. The MAF is an often-overlooked consumption part. They don’t just get dirty, they wear out.
I would get a code every 600 miles or so with my high flow cats. I picked up some 45 degree spacers for cheap and have never seen the issue again. Could never go back to stock cats personally.
It's the P 0420 BTW. What I want to know is....does the ECU do anything to try to adjust? I thought it only adjusted based on the upstream 02 sensor but I don't know for sure
Again, try the MAF. I had the same code, which is often the O2 sensor but not exclusively. My O2 sensors were pretty new. Replaced the MAF and no more code. Of course, YMMV.
Same here. A MAF is cheap and seems to be the center of alot of cels. July 2021 I had the same code P0420 as well as P1109 and P0172, which at first glance were suggesting OXY sensors. But my oxy sensors were only a few years old and I was using extensions that worked for years. Didn't think I had a cat issue yet.
So i pulled out my Durametric which showed the P0420 possible fault cause as oxy sensors. However, P1109 and P0172 showed the possible fault cause as the MAF. So I replaced the MAF and all three codes went away. Oxy sensors and cats are fine. And the car actually ran better.
Don't know if a new MAF is the answer or if the OP has an oxy sensor issue or cat issue, but what I have found is the MAF seems to be the center of alot of cels. So I replace mine approximately every 5 years. It was about 4 years in July of 2021 that I had the cell issue so I replaced it early.
All good.
As already suggested replace the MAF sensor it's cheap and easy . I have a Boxster S and a 996 neither has cats . Both have simple spacers installed in the " post cat " position . Neither have thrown codes . The ECM is only looking for a difference between the pre and post O2 sensors . Installing spacers provides that difference .
Been running my Boxster since 2016 and the 996 is still new to me at 500 miles but enough data on the Boxster that the spacers work .
Yes, ECU adjusts according to the upstream sensor.
But downstream will through an emissions code if the downstream sensor does not see clean exhaust.
Replacing MAF is possibly a good idea.
But know that there have been a lot of brand new Bosch MAFs that have been bad.
Seeing these from multiple vendors.
I would log with a Durametric or other quality scan tool(I.e. Snap-on) and see what your MAF readings actually are at idle and under partial and WOT.
Then I'd replace the MAF with Bosch only from someone who is lenient about returns.
Thats funny you mention that because I bought a NGK MAF. I've had poor luck with bosch 02 sensors on my other car recently and replaced with denso.....and no problem. I'm thinking bosch is over rated. NGK plugs have always worked well and they are a japanese company so I'll give it a shot
If there's a choice, I always buy Bremi or Beru over Bosch.
You didn't mention what year your car is, but your comment about throttle delay makes me think maybe you have e-gas. If so, I have a brand new Bremi MAF. I bought it by mistake for my '99 and by the time I noticed I bought the wrong one, the return window had closed. They're $100 - $110 depending where you buy. I'll sell it for $70 including shipping.
Trust me I went with all three aftermarket versions in the last years they all failed or were bad out of the box
went with Porsche part no more problems
i recently had issues and it was the maf. Anyway I cleaned the maf with CRC, great, the car even runs better. It�s $12 a can. Im adding maf cleaning to my routine oil change Techron schedule for both cars. I remember cleaning the maf from my vw days, it seems like it was always a good thing to do.
This works.
Techron is always a great idea. The parts stores normally do a bogo that�s when I�ll stock up. I use this on all my cars.
