Catalytic converter heat shield fell off

it will be a problem as the heat shield is there i to stop the floor from getting hot. It stops heat from going to other areas (fuel lines ,wiring harnesses )and causing problems

Sounds like a problem with the torkconverter

The most likely reason is when the new cat was installed, the mechanic did not reinstall the stock heat shield that protects the floor from the excessive heat of the catalytic converter. the heat shield either mounts to the floor underneath the car, about the converter, or mounts directly to the converter. Another possibility is that the heat shield was integral to the converter, and the converter that your mechanic installed was a cheap version that did not come with the required heat shield. Either way, I would suggest you try to get the problem resolved, as excessive heat from the converter could cause a whole host of issues.

SECTION 309-00: Exhaust System 2002 Taurus/Sable Workshop Manual REMOVAL AND INSTALLATION Dual Converter Y-Pipe -3.0L (2V)
Special Tool(s) 3 Bar Engine Support
303-290A Engine Lifting Brackets (3.0L 2V)
303-050 (T70P-6000) or equivalent Removal

1. Disconnect the negative battery cable. For additional information, refer to Section 414-01 .

1. Remove the bolts and engine roll restrictor.

1. Remove the bolt, ground strap, and nut.

1. Raise and support the vehicle. For additional information, refer to Section 100-02 .

1. Remove the splash shield and the air deflector.

1. Disconnect the catalyst monitor sensor (CMS) electrical connectors.

1. Remove the nut and position the heat shield out of the way.

1. Remove the nut.

1. Remove the nut.

1. NOTE: Support the exhaust with mechanic's wire.
   Remove the nuts and disconnect the three-way catalytic converter from the dual converter Y-pipe.

1. Lower the vehicle.

1. Remove the nuts.

1. Remove the bolt.

1. Using the special tools, raise the front of the engine.

1. Raise the vehicle.

1. Remove the bolt.

1. CAUTION: The sharp edges on the converter can cut the CV joint boot. Make sure to protect the half-shaft boot with a suitable covering before removing the converter assembly.
   Remove the dual Y-pipe converter assembly.

1. Remove the gaskets and, if necessary, the catalyst monitor sensors (CMS).
   • Discard the gaskets.

If you drive on gravel roads it may be gravel inside the shell,covering the converter this is the heat shield,or it may be loose and vibrating.Check fot any of the exhaust grounding out against the frameworks. If you have or can barrow a rubber mallot use it to beat on the converter pipe close to the converter ,you may find the noise related problem,look for loose hangers or clamps.

Most likely the heat shield has corroded off and is just sitting on top of the muffler or Catalytic converter. Regardless you can remove the shield and still run the the Xterra without any problems, the OEM muffler came with a heat shield as to the after market mufflers don't have one. The Catalytic converter also has a shield and you can remove it also as the Xterra has a heat shield on the floor board it self. Most exhaust shop if honest will tell you to just remove the rattling shield if there is no exhaust leaks or no Check engine light on that monitor's the Catalytic converter's performance.
A muffler shop if shady may advise you to replace the Catalytic converter and that can go for up to and beyond $400.00, so as long as there is no leaks or check engine light on. Go right ahead and remove the rattling shield.
Thank you for using Fixya

sounds like you have something loose first track were the noise is coming from and inspect the area for loose componets if it is coming from your motor then you might need a mechanic to check it out could be something loose in there

If it is the heat shield , any muffler shop can put a couple of welds on it. Could also be that the cat converter is destroyed inside with pieces of it ratling around. In that cast a new cat is the only answer.

It's likely the heat shield for the catalytic converter. There's really no repair for it. Mechanics won't usually spot weld it and they can't remove it. Apart from a little rattle now and then, there's really nothing to worry about.

I was just wondering if it is the cadilac converter