Z06Vette.com - Corvette Z06 Forum

seamus2154 · 06-18-2008, 09:27 PM

Planning a road trip to NYC this week so of course my engine light is on. Actually it's been on and I forgot about it on my to do list! Well because of the trip I took it in today. Onstar said it was emissions. Dealer said both Cats are bad and had to order the parts. I'm leaving Fri., probably w/o the repair I'm sure. Do you think I will have a problem? Tech said he has only seen this once and that guy drove the car for a month bfr the repair. Of course I got the party line that they couldn't guarantee I wouldn't have a problem. I would hate to be in limp mode for 1400 mls!!! Has anyone heard of this cat problem? I'm not modded at all yet. They cleared the code and no engine light for 75 mls. Thanks for any insight Jim

extanker · 06-19-2008, 08:33 AM

without knowing what # code i cant advise.did the dealer say its okay to drive ?

Tampap999 · 06-19-2008, 11:04 AM

Had the same issue last month. Apparently, there is a problem with the cats on '08s. It's been on back order now for 4 weeks. Called GM customer service this past Tuesday and the Cats were at the dealer yesterday. Getting them replaced on Friday. Also, dealer reset the light for me as well but it'll come on again after a day or so...the issue is related to the sensor also. Advised me that it's ok to drive the car, no problem. I haven't noticed anything different the last month I've been driving it.

seamus2154 · 06-19-2008, 06:00 PM

No they wouldn't say that I won't have a problem. I have been driving it for a while w/ the light on and also no problems so far . I'm just concerned about the longer driving times. My alternative is to drive the wifes VW Jetta diesel up to NY...not very exciting. So is the fix for this 08 cat problem the same as the rocker arm problem, put the same part # in and hope the warranty runs out bfr it happens again? Is the new cat different?

Tampap999 · 06-22-2008, 04:00 PM

Here's the info from my service ticket: Diag. Scantest found DTC P0420. They replaced the Left Cat. Converter and the Seals. It also noted " SOP Part is in Implosion". Not sure if something inside the Cat imploded but the next time I stop by the dealer, I want to ask him to explain the "implosion" reference. No problems so far...put 500 miles on since the repair.

TLewis4095 · 06-22-2008, 06:44 PM

Yes, the cats serated design can break up & start to cause obstruction & throw codes. They are not designed for the hi-flow needed when these motors are run hard. This has been an issue since the 95 C5 was released & the increased flow of the LS7 just compounds the problem. Only real soultinon is a good set of high flow cats & the rear O2's programed out.....but then you have an issue w/warranty if they want to be picky.

c4c5specialist · 07-02-2008, 07:43 AM

HI there,
The P0420 is for lack of oxidation capability.
Either the converter is coated and cant oxidize correctly, in which case you should be fine.
OR the converter broke apart and could create a restriction which could lead to power loss.
Either way, for the most part, you should be ok to drive but if you notice a loss of power and lower fuel mileage, chances are your restriction presented itself.
Allthebest, c4c5

seamus2154 · 07-02-2008, 06:02 PM

Thanks guys! I went on the trip over 3000 mls and no problems. Averaged 24 mpg and one day got 27 for half a day. Then hit heavy rain slowed and only got 21 mpg I guess from the resistence thru the puddles. Took the Blue Ridge Parkway coming back and really put her thru her paces. Cats still aren't in yet.