HibachiZ28

iTrader: (5)

So on Monday I drove in what was the heaviest rain I've ever been in. Not just in this car, but ever. 30 in the highway and still hydroplaning. On Wednesday morning my CEL came on while in traffic heading to work. I check it today and the code it's showing me is the "P0420 Catalyst Efficiency Below Threshold Bank 1".

I just filled up last night and my Mon/Tues/Weds tank of gas averaged 20.5 MPG, which is the best I've hit yet. I drive the same route every day to/from work in the same traffic, at the same times, so my habits are all the same.

Anywho, for our cars, does this just mean a bad o2, bad cat, or something else?

Thanks...

RsSean

iTrader: (27)

Driver side cat is bad. there was a bulliten out for GM to replaced them 10yrs 120k miles which ever came first but i am thinking your talking out the TA in your sig.

You may want to try and see if they will still honor it. You never know, if not time for some long tubes.

special coverage 05513 Catalytic Converter Extended Warranty

Doc id#1873709

Hope that helps

HibachiZ28

iTrader: (5)

Yes, this is for the 98 TA. It has 89k miles on it. I'll shoot a call to my buddy at GM and have him run my VIN # to check for un-filled recalls.

TransAmWS.6

Your drivers side cat is bad for sure, it can sometimes be the O2 sensor, but I'm pretty sure most of the time it's the drivers side cat when you get that code.

I had the same exact problem as you about a month ago with my SS, my drivers side cat went bad. Surprisingly, I was also able to get reasonable gas mileage and the car actually ran just about normal. I drove around on a bad cat for a little over 1k miles and it did fine the entire time.

If GM won't cover it under warranty, which wouldn't surprise me if they didn't, a good cheap alternative would be to just ditch the cats completely. I'm running an O/R Y through the stock manifolds and catback, it sounds pretty good actually and would probably sound better on yours since you have an aftermarket catback. If you plan on doing LT's anytime soon forget about it, but if not it's something to consider.

Marc 85Z28

iTrader: (8)

Don't bother. That "recall" only covered 2000-2002 models. Even if it did cover your model year, it's been longer than 10 years since it went in service.

HibachiZ28

iTrader: (5)

Well.. drove a couple thousands miles to, around, and back from Hatteras Island in the OBX. The light went off while down there and has not come back on.