P0430- catalyst system efficiency below threshold. CEL came on so I had it ran. ^ that is the code it gave me. Truck was running fine with the light on, actually seemed like it was running better, but prolly just an allusion of the mind. So I just reset the computer, and the light hasnt come back on and its still running fine. Any clues what might have caused this. Oh and I also ran a full bottle of that chevron techron stuff in it after i reset the computer

 

It basically means that the oxygen sensor behind the catalytic converter (called the downstream sensor) thinks that the catalytic converter isn't working properly.

If it doesn't come back, I'd let it go. At some point though, you may want to think about replacing the catalytic converter. How many miles on your truck?

And on a side note, how do you like your Firestone Destination M/Ts? I'm thinking of getting either those or the Destination A/Ts for my next set of tires.

 

Trucks got approx. 145xxx on it. Just had the downstream sensor replaced about a year ago. But I like the tires alot. never got the truck struck yet. They are the best in light snow, but I think they are the best off road tires. Had it out in the sand going up steep hills in 4hi and never ever had a problem with them