So i have been having some problems with my car i thought it was the transmission but took it to a specialist who said it wasn't and was most likely the cat. I took it to the chevy dealer who checked the computer codes, charged me 100 bucks and told me there was nothing wrong with it. Have any of you had a problem with the cat and it did not show up on the codes? Also what did the dealer say on the replacements because they told me they didnt have the equipment to check the cat. Any help would be great. Thanks.

 

yeah if the cat is bad or going bad it will resemble transmission problems, goto a reputable exhaust shop and let them check it out

 

A bad cat WON'T throw codes. How many miles on your Monte? I agree, take it to a reputable garage and have it pressure tested. I'll bet that if it seems low on power, and shifts funny, then you have a bad cat.
GM has a 100,000 mi warranty on your catalytic convertor. I had mine replaced, then had GM send me a check to cover the cost of the repair, labor and parts. REAL common problem!

 

My Monte has 53000 on it

 

My cat' went out at 83,000. I blew my tranny at 53,000. Reverse went out. It was UGLY, SOUNDED UGLY! I don't think you have tranny problems, with as many cat' problems as there are.

 

The problem that i have is that i already took it to the dealer. He said that if the cat was bad i wouldnt even be able to drive it. haha. ANyways they refused to test it and charged me 100 bucks so i dont know how to go about getting it replaced and/or tested.

 

SCREW THE DEALER! take it to a good garage.

 

AMEN, sorry to of put it so bluntly there but yeah the dealer is moreorless a ripoff artist. they dont know crap dont do crap. when i had a prob a while ago dealer charged me 100 to tell me nothin was wrong but yet the prob kept up and kept up and finally i took it to a reputable garage and found out my starter was going south. in all honestly i think the entire MCF is in agreeance goto a good shop and have them test your cat.

 

If a computer or scanner can't diagnose the problem, the dealer can't fix it! THEY ARE ALL MO-RONS! Sorry, but they get me frustrated! It's a pretty simple check. They drill 2 holes, 1st in front of the cat, and the 2nd behind it, and hook up their pressure guage to check pressure. Should cost $25 to have it checked, and $250-$300 to get it fixed, total. NAPA cat' is just over $200. They you contact GM and go thru the paperwork to get re-imbursed. Two months later you get a check.
You can do a simple test yourself. Put someone in the drivers seat. Put your hand over the exhaust tip, and have them rev it up a couple of times. You should feel the difference in pressure, and if not, you got a problem.

 

Actually that is a bad statement as it will throw codes. P420. It just doesn't do it all the time even if it is bad. You can't rely on the cat to throw a code if it is bad.