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Showing content with the highest reputation on 10/19/2017 in all areas

  1. Replaced the Y pipe. Almost one month and no more problems.
    1 point
  2. Leaky pipe after O2 sensor under heat shield. Common problem. Easy fix, weld the leak. Never was the CAT.
    1 point
  3. Well my P0430 saga is over I think. Today I removed the Y pipe and secondary catalytic converter section to get it on the bench. I removed the stainless steel heat shields and sure enough on the Bank 2 side the pipe was cracked almost all the way around. The crack was about 6" behind the secondary O2 sensor hidden under the shield. See photos below. So I reinstalled the Y pipe with finger tight bolts just to get it aligned properly. Then I tack welded the pipe (MIG welder with flux core wire, no gas) so it would stay in the proper orientation. I then pulled the pipe back out and got it on the bench for a thorough welding. It’s really a job for a TIG welder but since I don’t have one I plodded on with my MIG welder. It isn’t a work of beauty but I got the pipe strengthened and plugged up of all the leaks. Then went on to puddle weld the other areas where the shield clamps had existed (and the exhaust pipe was about to corrode through). I figured while I was at it I might as well strengthen those areas. After I was done I didn’t reinstall the stainless steel heat shields (last photo at bottom) as the fiberglass insulation was damaged beyond use and some of the bumps from welding would have interfered with a proper fit. Maybe someday I’ll get ambitious and put them on but I doubt it’s anytime soon. I decided to remove the replacement non-OEM catalytic converter I installed back in August and reinstalled the old OEM one. Using new OEM gaskets and bolts throughout, reinstall was a snap. I had bought a new O2 sensor for the Bank 2 secondary side but didn’t install it either. I also didn’t use the O2 sensor spacers I had been experimenting with (spoofing emission system so it didn’t see erroneous bank 2 secondary O2 sensor). Fired up car and it was immediately more silent than before. Recently the leak had gotten to the point that it was becoming quite audible. Now it was back like it was before all this trouble. I went for a test drive with my OBDII adapter and laptop. I watched the bank 2 primary and secondary O2 sensors on a graph output. Lexus LS430 O2 Sensor Graphs.pdf I knew right away all my P0430 problems were fixed. The secondary O2 sensor was stable, mid voltage range and only moved a little. It closely mirrored the bank 1 secondary sensor. Prior to this the bank 2 secondary sensor tracked the bank 2 primary sensor. That is why I thought I had a bum catalytic converter. I’ve since driven 80 miles or so and no CEL. It might take a couple days to run all the ECU tests but I am very confident this has solved the problem due to the radical change in the bank 2 secondary sensor output after welding the leak. Lessons learned: This was never a failed catalytic converter problem as some suggested (DAY). I am very happy I didn’t buy a $1,000 OEM primary catalytic converter or $1300 OEM Y-pipe/secondary catalytic converter. I still don’t understand why a leak well after the second O2 sensor can have such a dramatic impact on secondary O2 sensor readings. While I don’t understand it, I have seen very clearly with leak and without (repaired) leak. The difference is unmistakable. I wasted some money on parts I didn’t need. $60 on a bank 2 primary O2 sensor, $175 non OEM catalytic converter, and another $60 on a secondary O2 sensor. I’ll leave the primary O2 sensor in as it’s not worth my time to pull it out. I’ll see if I can sell the slightly used converter and new unused secondary O2 sensor on eBay. The design of the Y pipe and secondary catalytic converter is poor. The stainless shield and salt water wicking insulation sets up a perfect corrosion environment for the exhaust pipe to develop leaks. I suspect a lot of LS430 owners will start seeing P0420 and P0430 error codes. My salty home state of IL contributed to my 2004 happening so fast. I learned a bit about OBDII and emission control system in general. Always use OEM gaskets when removing these parts. The gaskets that came with my non OEM catalytic converter were laughable. I made a listening device with 2’ of clear tubing connected to the ear piece of my mechanics stethoscope. It made probing for leaks simple and precise. In fact I found a couple pinhole leaks after I was done that I was able to plug up with a couple of MIG shots. If you get a P0420 or P0430 don’t run out and change catalytic converters. It may be as simple as a pipe crack underneath the stainless steel heat shields.
    1 point
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