Hi All, I suddenly started to get a p0421 & p0431 CEL code on my '07
Cayman S
. It seems to go away and come back randomly. The only thing that I can seem to correlate with it is it happens on colder mornings. Anyways, viewing the voltages for the o2 sensors, I can see that the bank 2 after-cat (downstream) sensor sits at .60 while bank 1 sits at .80. Could this be indicative of a bad sensor? I believe if it was a bad cat it would be fluctuating with the lean/rich cycle as the upstream sensor does. Any thoughts/ideas? Thanks!
I had a similar situation a few months ago. I ended replacing both cats. At first, only one bank was reporting poor efficiency, then both did.
If your car consumes any oil, it’s probably time.
I got new Magnaflow emissions compliant replacements for both sides at hottexhaust.com. They’re running a 25% off fall sale right now if you click their “2018 coupons” link. Both cats will be about $650 total after the discount.
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I was running the same codes only all the time regardless of outside temp. I would clear and get back within a day or so. Much research and discussions in the header market for our cars. My choice was Soul Performance catted headers with new O2 sensors up and down stream of the cats. Installed a couple of days ago. Great quality and perfect fitment. I had Magnaflow on order and spoke to Meatful on the forum. More conversation with a very honest and forthcoming distributor, I cancelled my order. Here are the pictures from Meatful's purchase.
https://www.planet-9.com/987-cayman-and-boxster-chat/234055-magnaflow-headers-pics.html?highlight=magnaflow
After a conversation with John at Soul Performance, I was sold on their headers. They are every bit as good looking as they show in the posts and vids. The sound is much deeper than stock headers and a more refined note. Under 4000 rpm, they are very nice and refined without too loud. I am 57 years old and do not care to scream around the neighborhood. At 6000 rpm they are tearing the tips off. Cannot wait to get to the track and really unwind. Also, the drone from 2300 to 3000 rpm is much less with the new headers.
My input, pictures and video links are here
https://www.planet-9.com/987-cayman...ications/200513-soul-performance-products-987-1-exhaust-headers-showcase-4.html
My choice was to spend more money on the much better quality and what appears to be science and testing on the product. Needless to say, made with skill and pride. A lot more money than the Magnaflow but there is usually a good reason something is cheaper.
Lastly, 3 days since install and no codes. Good luck with your decision.
