Ok so my stupid Cobalt is now throwing a new code. P0420 Catalyst System Low Efficiency ECM, PCM. Chevy told me it was more than likely my spark plugs so to try that first, I did...didn't help. And the car is driving like absolute ****. If I go full throttle the RPMS jump all the way up and the engine revs and the boost gauge boosts but the car does not respond. I swear whenever I get this code cleared this car is finding itself in someone elses hands. I've gone completely back to stock to get rid of codes and now it's giving me brand new ones.

 

What mods have been done to the car?

 

As of this moment it's stock and hasn't had any mods on it for many months.

 

oh and by the way ive noticed a terrible drop in gas mileage as well.

 

dude sounds like you got a demon balt. though i have to say the tc's have had a lot of problems compared to my 2.4. my suggestion if u like the balt, sell that one get a used one with around 40k on it. if its survived that long its likely all the kinks are worked out of it by now haha

 

sounds like your cat is clogged cut it off so then you will have a reason for it to show that. Im 99% sure its a clogged cat.

time for catless dp and zzp pcm tune

 

Oh I plan on selling it but I gotta get this issue fixed first. Dealers around here are all about knocking $1500 off your car value for a MIL

 

Can you rev all the way to red line?

 

dont know if codes are the same but on a tc that is the code for the cat

 

yes I can.

 

sounds like clutch slippage if u can rev and the car doesnt respond...

 

cat is under warranty. thats a catalyst inefficiency code. tell your dealer they are retards

 

God I hope not.

 

The cat isnt clogged or at least not horribly. Possible its the O2 sensor

 

So take it to dealer and bring up cat problems?

 

unbolt downpipe, jam a large rod into the end closest to the cat until it can freely go through, then buy new gaskets and bolt the dp back up






or you could just get the 120,000 mile cat replacement. but its not as fun as taking out your anger on your catylitic converter

 

yes thats what check engine lights are for. dealers are retarded

 

1. The code means either the cat is toast or the second O2 sensor is shot.
2. If you go WOT and the RPMs jump to redline but the car isn't moving then you need a new clutch.

 

sigh #2 scares the hell outta me. How much do you think a new clutch and installation will run me?

 

po420 cat is bad have it replaced under warrenty I work for a dealer i have seen that code many of times.

 

Dealerships look so hard to prove the check engine lights and codes wrong. They never seem to look at the obvious they just want to screw the customer.

 

Thank you very much.

 

I think a clutch + install usually runs $1000 - $1500 or somewhere around there.

 

calls for 8+ hours FOR CLUTCH REPLACEMENT and shops usually charge about 50-80$ a hour so yeah, i can get you a clutch kit for 350 pressure plate throw out bearing and friction dissc, itll hold up to 600ft lbs iam running it, and it holds up great. If you were down here id charge you 750 for parts and labor

 

po420 is a cat code which mens either cat is bad or the 02 sensor is bad or a exaust leak.