Steam around O2 sensor, engine whistle and a Cat-related engine code

[2001_XJ_daily]

I've been wrenching on a new-to-me daily driver 2001 XJ Sport (4.0, 4x4, auto, 153K, stock, no lift, never off-road) all summer, and am sort of stumped on a new issue, which I originally thought was a failing cat.

OBD is throwing code P0432 [Catalyst Efficieny Fault Bank 2], which usually means a dead/dying cat. I'm getting ok mileage, but running rich. No rotten egg smell.

My main concern with the cat is that I used a can of Sea Foam fuel additive about 6 weeks ago and clogged it up. I did this without diving into all the warnings against doing so, so I feel like an idiot because the code popped up shortly afterward.

But I'm also having two other issues which seem related. (If not, I must just be lucky.)

1. There is a loud whistle coming from the engine bay when throttle is applied; it is not there at idle, and I can't determine a source. (I tried using propane to find leaks and found nothing, but I've never done that before.) 

2. The other is steam originating from around my downstream front O2 sensor. There seems to be some sort of liquid on the pipe, but I can't figure out what it is/where it's coming from, or if that's the issue at all. I know the code refers to the rear cyl bank, but is this relevant.


Some other mods/new parts that may be relevant:

• all new plugs in August

• all four O2 sensors (NTK) were replaced by me less than a month ago
• there may be an oil pan/RMS leak (you can see the dirty slick in the vid), but have not addressed it yet. 

• I did stop an oil leak by replacing the o-rings on the oil filter adapter also less than a month ago
• this past July I replaced the valve cover gasket and oil pressure sending unit.

Fluids seem full, and there is nothing leaking onto the ground as far as I can tell. There doesn't seem to be any fresh fluid directly above the steam issue. I don't

See the videos here:

• looking up through engine at O2 sensors (top of video is front of Jeep) - you can also hear a loud ticking sound that I can't locate either: https://youtu.be/42QDU6ZpZIo

• applying throttle to generate whistle: https://youtu.be/kMNvf6sSmDY

Any questions/advice are appreciated! Love these forums – they've been a huge help all summer.

 

[RCP Phx]

As for the steam, I'd say you have either have a oil leak or possibly a leaking freeze plug.

 

[Tim_MN]

A whistle is most likely an intake leak or a vacuum leak. Stream, I would suspect a failed head gasket or 0331 cylinder head cracking.

Coolant leaks can kill O2 sensors and cat converters.

 

[Ralph77]

What I would like to know is did you get the P0432 code then do the O2 sensors?
Or the other way around?
I had the same code in my '00.
While researching it looked like exhaust leaks, O2 sensors, and fuel trims could cause this too.
Once I ruled out all the above best I could I replaced the cat.
Been fine every since.
I asked about you replacing the O2 sensors before or after cause if you have a lazy O2 sensor, not working properly but not enough to throw a CEL, it could be playing nice with a not entirely proper operating front cat.
So now you throw in brand new operating perfectly O2 sensors.
And ends up throwing the code cause you have a not entirely proper operating cat.
I believe this is what happened to me cause I replaced my O2 sensors that had about a 150K on them thinking they needed to go and sure enough.
P0432. LOL.

 

[89Mock]

My Jeep has a pinhole in the rear freeze plug that looked just like a rear main seal. Definitely more involved to replace it and the rear main definitely isn’t bad.

 

[89Mock]

Did this get fixed?