I've got a 2008 JKU w/ automatic transmission. I'm thinking my catalytic converter(s) is clogged and needs to be replaced. Service manual makes it sound pretty simple:

1. Raise and support the vehicle.
2. Saturate the bolts (1) and nuts with heat valve lubricant. Allow 5 minutes for penetration.
3. Disconnect oxygen sensor electrical connectors.
4. Remove the nuts from the front exhaust pipe and catalytic converter assembly to muffler flange.
5. Remove bolts (1) and flanged nuts at the manifold.
6. Lower the front exhaust pipe/catalytic converter assembly (3) and slide out of the mount at the transmission (if equipped).
7. Remove the front exhaust pipe/catalytic converter assembly from the vehicle.



Question --> Assuming I can get these nuts and bolts loose, will the cat assembly/Y pipe slip out as an assembly without removing other stuff? Anyone else done this and have any tips? I've looked for other threads and can't find anything.

 

CATs dont plug up on their own....they OVER HEAT & MELT (usually from an improper air/fuel mixture).

What symptoms are you experiencing that make you think your cat is bad ?

its gonna be an expensive endeavor, not including new O2 sensors and other parts that damaged the cats.

http://www.catalyticconverterwarehou...Vin%201@@36279

http://www.discountcatalyticconverte...nts=partfinder

 

Here's my check engine light saga:

• EGR & O2 sensor codes for bank 2, sensor 1 show up
• Replaced EGR valve and plugs - EGR code goes away, BUT
• Getting the same o2 code (p0152) and p0300 (multiple random misfire)
• Clean out throttle body and replace gasket - still getting same codes
• Replace coil pack and PCV valve - still getting p0152 & p0300
• Spark plug wires look good

I've noticed my jeep will throw the misfire & o2 code after I've been driving for a while and usually while accelerating - right about the time my transmission shifts into overdrive. When this happens, it's like my jeep bogs down for a while, then surges when it's worked it out after a few seconds and if I let off the gas. Also, it idles rough after warm up even when no light is on. I don't have any rotten egg smell from exhaust, but I have had some oil consumption issues historically with my jeep. Usually about 2 quarts shy of the 6 I put in at every oil change at about every 4k miles.

 

if a cat melts/plugs up and restricts the airflow you'll definitely feel a decrease in power.
a down stream (bad) o2, can cause the mixture to change and cause over heating of the cat.

the bad (as in not failed but supplying false data) downstream component can make the upstream components LOOK as though theyre not functioning properly.

rather than just replacing parts (and I'm not saying you have) - id be looking for information & procedure to properly test components (w/ a multimeter) to help determine what if any part might be causing the problem.