So I thought I had all the codes figured out.

And it seems like just to screw with me now, when I hope in it and drive it before it fully gets up to operating temperature if I have to stop at a stop light applying the brake in drive. It will flag this code, if I clear it, once I get operating temperature it never comes back. Until the engine gets a chance to cool all the way back down. What's funny is I've been running these aggressive fuel system cleaners trying to take care of my P0 301, and seems like that code went away, I'm wondering if the concentrated fuel system cleaners might have caused damage to my catalytic converter causing it to be low efficiency, if anything I would have thought it would have cleaned the system out. What you guys think my vehicle is an 07 2.4 LT automatic trans

 

It would depend on the age of your catalytic converter, is it OEM? Have a read, this cured my P0420

https://www.chevyhhr.net/forums/2-2l...20-code-58413/

 

yes its original 150kmiles... i'v put about 1K miles on it since i'v owned it, not at any point has it had this code until now. I am thinking there might be large chunks of carbon that has broken off my exhaust valves, as i was getting p0301.... from day one... a girl owned it for the last 50 k miles... witch is good and bad. i have been running concentrated fuel system cleaners... and even removed CYL#1 plug and blasted chemtool b12 in there and cleaned it out individually... but the hard trip from mi to the poconos pa, with all that concentrated fuel system cleaner in the gas, is what cured my p0301.

 

Yes the P0301, is cured. That cleaner could have tripped the P0420, mine was from oil getting sucked out of the valve cover. Moving the second O2 sensor out just one spacer has resolved my issue and it might for you. You could run a can or two of Seafoam or Cat-Clean it might also cure the issue.

 

Either the p0301 or the chemicals cooked the cat.

 

I guess for now i will keep driving it and clearing the code.

interesting how that spacer worked for you though.... i guess a spacer is cheaper then a new sensor :)

 

Go figure! It's worth a try at least! I haven't had the code pending or otherwise since Feb 8, 2017.

 

This. Who knows how long it's been misfiring.

 

Why are you clearing the code? Every time you do, the OBD2 tests cycle has to start over. If the light bothers you put some black tape over it.

The P0420 means that the sensor is good!

 

hang on i had to install adblock... the forum is an adwhore...

i am trying to figure out if i want to butt heads with the "TECH mod" here...
The light doesn't bother me. after i tap the erase on my little code reader i have hanging from the turn sig its fine and it stays off. Until the car is cold again.

I am 37 years old not once have i ever needed to replace a cat, and as higher millage cars are drawn to me, they always get Tons of miles.

no need to start replacing cats now.... if anything i pop in a resistor satisfy the downstream. we dont have those retarded inspections here in mi... so no need to satisfy some pencil pusher.

i didn't suggest i change the down stream... that whole thing was from something else.

who knows how long the person before me drove it with a p0301.... that is a good question..... when i changed the plugs they were probably original....

if the tech mod bothers me can i put tape on them ? lol