Solving my P0420, Need Advice

I have a P0420 error on bank 1 (pass. side) of my 2006 TRD Taco. Troubleshooting the error I have determined the gasket between the primary and secondary cats is leaking when cold. It’s the one pointed to by the arrow in the picture.



What is the best approach to replace that one gasket?

(1) Is there enough wiggle room that I can break the connection at the flange and pull the downstream exhaust back to remove the old gasket and clean?

Or

(2) Remove the short section containing the downstream oxygen sensor and the secondary cat? The section is visible in the same diagram above. Again will I be able to pull back on the downstream exhaust to make enough room to remove the short section. I’m guessing I will need 4 inches to clear studs and any internal mating surfaces.

I’m trying to repair the one gasket that is bad without damaging the other gaskets in the system. I figure the cross-over might give me fits.

Your thoughts, recommendations?

Whitedog

PS I found the leak by blowing low pressure air in from the exhaust pipe using my shop vac. You tube video !

 

I've removed the crossover/y-pipe to install an aftermarket URD y-pipe. I seem to remember the passenger side being fairly rigid so at the very least, I would have the two gaskets ready to be able to remove the entire short cat pipe (17410) and replace with fresh gaskets on both ends if you need to. I feel like the rest of the y-pipe has enough "give" to allow removal of 17410 without loosening and disturbing the other gaskets. I also remember the flange you have pictured giving me mountains of trouble. First, the external Torx stud stripped, then the whole thing sheared flush when I put vise grips on the stud. I did manage to bulls-eye and center punch the remaining stud and was able to drill it out without damaging the flange. Long and short of it, take your time, use lots of heat and lube (candle wax works great lubing exhaust hardware after you've put a torch to it). Good luck!

 

desertratliff

My thanks for your time. I agree with you ; removing the short section and replacing both gaskets. I did not pay attention to the torx nuts on the subject flange. Do I need an external torx socket or does it require a normal six point hex socket? I gather the stubs are welded to the forward flange?

It looks like the rear flange (at the other end of the short section) uses simple bolts and nuts?

Plus lots or penetrating oil and patience.

 

I had that same code, same location. I replaced both gaskets. Used a ratchet strap to pull the exhaust back to replace them.

 

Thank you Larzzzz.

I was thinking the same thing, using a simple ratchet strap.

 

I had the same issue with mine. I was getting a P0420 and randomly a P0430, which is the drivers side. To remove just the passenger side it'll be pretty tight without removal of the drivers side. It is doable if you don't want to take that side off. I didn't use a torx and remove the studs, simply the 14mm bolts. Make certain to use some penetrating fluid on the hardware. Also I dropped a few of the exhaust hangers to let the exhaust come down further. Use a good amount of WD40 to get the hangers off.

I'd recommend trying just the passenger side first. If its too tight, pull the drivers side down.

 

avery0829,

Thanks for the reply. Will take my time.