Has anyone experienced a rattle at the catalytic converters?

[Password]

I've had the rattle for awhile and it's consistent through fast idle at startup and continues after engine is warm. It will get louder when accelerating. I laid under the truck while it was in fast idle and it really sounded like it was the cats (sound was from both). I meant to grab the wastegate linkages but ADD kicked in and I put the covers back on and cleaned up for the day.

BTW, I'm assuming the larger diameter cans that are running down before the exhaust is horizontal are the cats on both sides.

 

[JerryT]

I had the same rattle like noise but found it came from a loose oxygen sensor. Actually both were loose. I tightened them up and rattle disappeared. You need a special socket to tighten the O2 sensors.

 

[sjwhiteley]

I have a rattle on cold startup which sounds exactly like you are describing, directly under the vehicle. However, it goes away after around 30 seconds of idling, and not present when engine is warm. Definitely not the engine, definitely not the turbos.

 

[Dsurkamp]

What kind of special socket do you need to tighten them up?

 

[99WhiteC5Coupe]

What kind of special socket do you need to tighten them up?

An oxygen sensor socket (the socket is hardened and has a cut-out on the side for the sensor wiring).

 

[Password]

O2 sensors were tight......it was the wastegate linkages. Seems so strange because it can be heard through the exhaust system.