Catalytic Converter Tick and P0420/P0430 Codes

[DTCsk8er]

There are probably hundreds of us here running around with the exhaust manifold tick and no P0430/P0420 codes lit; that being said, on other vehicles, this is quite common when a leak is present ahead of the o2/cat(s). My wifes Jeep JK has this code, and I found a crack in the exhaust manifold, so that is getting swapped out. My cruiser ticks when cold, and barely anything ticking while hot. Its on the list of junk that needs fixing, but so far, 50k miles (and who knows how much longer before I bought it), not a problem has resulted from it.

Usually for this code, I check the exhaust for leaks using a smoke machine. Get an OBD2 reader, and observe the o2 voltages, and fuel trims after a good drive.

 

[2001LC]

I checked the resistance on the downstream O2 sensors. One reads in ohms 13.3 driver. And 13.1 pass. Someone said they should have 16 ohms resistance? Is this right? I am about to check the spark plug torque next. Ordered some cataclean so that will be third. Any help?

For 2003 (likely all O2's. Not to be confused with A/F sensor, which are sensors 1 BK 1 & 2 of VVT engine 06-07)
Using an ohmmeter, measure the resistance between terminal +B and HT. Resistance: 11 − 16 Ω at 20°C (68°F)

 

[VirginiaSlim]

I had a P0420 for couple months with CEL and VSC lights on. Changed engine air filter, cleaned MAF and throttle body. Did not do anything, code still showing.

Finally got a new Denso downstream O2 sensor, let it sit overnight for gasket seal, then drove around some. Codes still showing.

Finally driving today the codes are off and have remained off. Just waiting for the OBD EVAP monitor to read so I can pass emissions.

TL; DR: had P0420; changed post-cat o2 in bank 1 sensor and codes resolved.

Update: my codes have remained off and my EVAP monitor finally cycled to "OK." My car passed the inspection (plug in to OBD port) this morning.

 

[5500lbs]

For the P0420 error code you should check for leaks in the exhaust system first, them try catalytic converter cleaner if that doesn’t solve it.

Is there a typical place to look for leaks? right at the manifold and head?