Catalytic Converter/Check Engine Light

[MTPockets]

Hi guys! It's been a LONG time since I have been on this forum! I have an issue with my 01 Wrangler that I'm hoping someone can help with. Last month I installed a Jasper remanufactured L6 engine. (#5 piston skirt self destructed at 153,000 miles.) Since then, everything is fine except the check engine light came on, throwing a P0420 code, which is a "Catalyst 1/1 efficiency below required level". I wondered if it was a bad sensor on bank 1 or a bad cat. I just took a 400 mile road trip and now, in addition to the P0420 code, I also get a P0432 code (Catalyst 2/1 efficiency below required level). I have been getting about 30 miles less per tank of gas but otherwise the engine is running fine. The 2001 TJ has 2 "mini cats" just off the exhaust manifold and a regular cat right before the muffler. Since the error code is on both banks I'm guessing the main cat is bad. I doubt both sensors would go at once. Since my bank account is a bit thin after the new engine, I'd rather not replace the main cat, both mini cats and all the O2 sensors if I don't have to! The old engine was burning a little oil because of the broken piston and I'm wondering if that could have fouled the cat enough to throw the codes. So what do you think? Replace the main cat, replace the mini cat(s), replace the O2 sensor(s), or replace the entire exhaust system and sell a kidney to pay for it?

Thanks so much in advance,
Scott

[Jim_Lou]

My though would be to replace the sensor on one bank, clear the codes and see what happens. If the bank with the new sensor throws a code again it's probably a bad cat there. If it doesn't throw a code, swap the new sensor with the one on the other bank. If that bank doesn't throw a code you should be good to go with a second new sensor.

[MTPockets]

Thanks! I'll try that and post the results. It may be a few weeks before I can find the cash and the time to get it done.