Catalytic converter or Gasoline ping???

I have a 2000 Jimmy SLE. There is a rattle or ping sometimes on acceleration or when idleing. The noise is not constant. I took the Jimmy to CarX and the guy said the catalytic converter is "melted or in other words has shrunk." Can this be obvious just looking at the undercarriage? I do not smell exhaust when I am driving with the windows open. I am going to have the codes read at AutoZone to see if an Oxygen sensor is bad or the EGR (the mechanic said those could be bad). Someone else said that it could be the gasoline. I use 87 grade from Mobile or Marathon. Are there any inexpensive things to try to see if it is just the gas or to definately know if it is the catalytic converter. To me, it sounds like a muffler pipe is loose (had one on a Plymouth van).
Any help and/or advice is greatly appreciated.

P.S. I did read other posts regarding catalytic converter.

go out in the morning when your exhaust is cool and shake your cat or gently bump it with a hammer. Its possible that the catalysts have melted or dislodged and are rattling around inside the cat.

Also, be sure to really get a good visual inspection and see if there is anything obviously rattling






I have a 2000 Jimmy SLE. There is a rattle or ping sometimes on acceleration or when idleing. The noise is not constant. I took the Jimmy to CarX and the guy said the catalytic converter is "melted or in other words has shrunk." Can this be obvious just looking at the undercarriage? I do not smell exhaust when I am driving with the windows open. I am going to have the codes read at AutoZone to see if an Oxygen sensor is bad or the EGR (the mechanic said those could be bad). Someone else said that it could be the gasoline. I use 87 grade from Mobile or Marathon. Are there any inexpensive things to try to see if it is just the gas or to definately know if it is the catalytic converter. To me, it sounds like a muffler pipe is loose (had one on a Plymouth van).
Any help and/or advice is greatly appreciated.

P.S. I did read other posts regarding catalytic converter.

I looked under the Jimmy. This is going to sound dumb, but I have no clue what the catalytic convert looks like. Tell me what I am looking for. Also, I took the Jimmy to AutoZone. There were no codes listed, the machine said "Pass". The "Service Engine Soon" light has never been on. The guy said if an O2 sensor, or any sensor was not working properly, the SES light would come on and the codes would be registered. So...is it just the catalytic converter that is bad or what? Any ideas?

your catalytic converter looks like a small muffler that comes before your muffler. If no codes are showing, I'd get under the truck when it is cool and look for a loose exhaust-pipe hanger. Also look for loose connections to the muffler. Your problem sounds like something mechanical like a loose muffler pipe. Get down there with a flashlight and look, touch, shake stuff, find that @#$%^ rattle !! Good Luck !



I looked under the Jimmy. This is going to sound dumb, but I have no clue what the catalytic convert looks like. Tell me what I am looking for. Also, I took the Jimmy to AutoZone. There were no codes listed, the machine said "Pass". The "Service Engine Soon" light has never been on. The guy said if an O2 sensor, or any sensor was not working properly, the SES light would come on and the codes would be registered. So...is it just the catalytic converter that is bad or what? Any ideas?