Poseidon99

I just bought this cayman s around middle may, I bought it with oil full and full transparency, the seller told me what needed work. He said the suspension was going, the brakes probably needed changed, and the AOS was bad.
i installed a new AOS within a couple of weeks cause i went from full oil to almost empty which I assumed was the culprit. Everything was fine until a couple weeks later I got a cylinder 1 misfire and a cat code.
i ended up changing all spark plugs and running cataclean through the gas tank.
Both went away, about a week later the cat code came back.
I’m open to any ideas or thoughts before I pull the trigger on new headers/cat as it is very expensive

oldbutslow

Put a bottle of Chevron Techron in it. I fought that code for years till I put that bottle in, which was almost 10K miles ago. I’ve been completely loyal to Chevron gas since then and that code has never come back.

Poseidon99

just Chevron Techron 93?

oldbutslow

Chevron puts Techron in all its grades. I use 91.

Poseidon99

could the cat code be the reason why I’m losing oil with no visible leaks

bredward

Cats are sometimes damaged (permanently) by unburnt fuel entering the exhaust system. It contacts the hot metal exhaust and combusts, which obviously producesheat, and excessive heat damages the precious metals in the catalytic converter. If you currently have an oil leak somewhere, I wonder if it's possible for it to end up in the cats, potentially clogging them and/or damaging them when it combusts.

dxrohanx

I read that the O2 sensors are wear items so after I got the same code I bit the bullet and replaced all four sensors ($450) on my 06 CS w/ 53K: two pre-cat and two post-cat on the stock exhaust. The code hasn't returned but that was my only symptom so it won't help with the oil consumption.

How much (quantity/bars over miles) are you losing after the AOS install? Was there a change in consumption after installing the new AOS?

oldbutslow

I’d get a handle on that oil consumption before attacking the cat code. A bad O2 sensor could possibly alter your AF ratio, but oil consumption should not be affected. I’d continue to drive the car, to verify the oil consumption, before firing the parts cannon at it. That cat code is more of an annoyance versus the oil issue.