Underblu

I’ve been having this intermittent P0420 CEL that I couldn’t get resolved at my local Porsche dealer. Don’t get me wrong, afaic its a fantastic dealership and their service department is very easy to work with, highly accommodating with some genuinely nice people. However this P0420 CEL was exasperating.

So I take my car to Deman Motorsport to have them take a look. Rick cordially welcomes me to the shop and shows me around, let me just say his 4.5 liter engines look like industrial works of art. We talk a bit about the 718 platform, you can tell immediately Rick’s a true Porsche enthusiast. We also have a nice conversation about mountain bikes and airplanes (turns out Rick is a pilot too) Anyway I leave the shop and figure if I’m lucky, maybe I’ll get my Spyder back in a few days. That very afternoon I get a call from Rick: he says he just took my car out for a post fix drive and all is good. I got my car back the same day! You can’t put a price on service like that. Turns out it wasn’t a catlytic converter efficiency issue at all but rather the valve on one side of the stock exhaust was loose. And as I recall correctly, the P0420 error message would tend to come on after a minor bump in the road.
(The only downside to this whole thing is that it should have been covered by Porsche under warranty afaic.) Anyway I drove the car home and no more CEL. Thanks Rick and the Deman team

DrainsWalletsFast

Is there a way to get reimbursed by Porsche for the work? I imagine not, but it seems like not a difficult argument to make with multiple receipts from the dealer being unable to help you and then an invoice from an independent shop who fixed it right away. Whether they'd care at all is another story.

Reedy

Sometimes you need to spend some money to get the right service. Glad it was just a simple vacuum leak. I will keep that in mind in case I ever get a P0420 myself.

Rick DeMan

Not a simple vacuum leak, had nothing to do with the vacuum system.

The factory valve had broken it's internal weld and would randomly do what ever it wanted.

BabyNSX

I find that the factory valves are VERY loose and tend to rattle a lot. Every time my valves open/close I can hear them rattle during the event. I'm not surprised that they could end up breaking... Didn't realize that a CEL would be a symptom but this is good to know.