So I have 420 and 430 codes so I am thinking I need to replace the cats. I just bought the car and I haven't thrown it up on my hoist yet to see what it looks like under there, but if the cats are the issue, what is the best/cheapest option?

a buddy says to throw resonators in place of them, others say straight pipe and then it's just replace with new cats...

I'm done with driving a loud car as a daily driver which is why I went with this car, so i want it to be fairly quiet, what is my best option?

 

2nd hand cats...dealing with the same issue myself; can't take that sulfur smell.

 

Welcome aboard Neverdone;
How many miles are on your LS? Not an uncommon problem to have a small hole develop in the Y pipe, which will cause the O2 sensor to throw a code for P0430. I haven't seen P0420 yet with this issue, however. I have a small crack in my 01's Y pipe which causes the ECU to throw P0430.
I would get it up off the ground and take a good look at the exhaust system before any radical decisions on swapping out the converters. These cats are fairly robust and will last a long time.

 

Thanks for your reply. The car currently has 260k kms on it(canadian) . I'm a welder, so I should be able to repair it if it's a hole or what not.

 

I'm wondering if the sulfur smell that fills my cabin at 60-70mph could be caused by something other than a bad catalytic converter...any thoughts gentlemen?

 

You may still have the thin heat shield metal around the Y pipe. If so, that may block your view during the search for cracks. My heat shield was removed and some cracks repaired by the original owner.

With no leaks, I did end up changing the passenger cat converter. The driver's side is (so far) holding in with closing in on 134k.

 

Just a heads up tampering with any emissions equipment on the vehicle is like a $2500 fine from the epa if you get caught, so is selling used emissions components.

"Title II of the EPA Clean Air Act (Enacted Jan 1 1988) there are multiple regulations concerning the use or misuse of aftermarket catalytic converters, or the removal and/or modification of a stock catalytic converter. According to various parts of Section 203, all aftermarket catalytic converters must be EPA certified, and your car must have a gas conversion device of some manner. If not, both you and the installer are punishable of a Federal Offense by Section 205 (a). The operator's fine can be no more than $2,500 and the installation agency no more than $25,000."

You can buy used converters but they must be from the same year('s) engine and transmission package as your car and must be tested and certified.

 

man, you're really hard about emissions around here lol we don't have emissions where I am so IDGAF

 

So since I have an '03 any used converter can only be from an '03?...or would one from a 2001-2003 work since the engine and transmission are the same?

 

I am just letting people know the law so they can weigh if its really worth it and why there shop or dealership will not remove there converter(s).

There on the car for a reason also they have a minuscule effect on hp and tq.

 

You can get one from an 01-03 sorry about that I made a typo as long as it has the same motor and transmission it is legal, but I do not think that the 04-06 converters were different than the 01-03. I am not 100% though but I highly doubt lexus reengineered a completely different converter.

 

I don't think the converters would be any different and I'm quite positive the engines are basically identical but didn't Lexus introduce a 6spd for the '04-06?

 

I was just putting the law up there so people will understand if a shop tells them no they wont touch the converters. The engines are the same for 01-06, the only change was the 6spd transmission in the 04-06 but I highly doubt the converters are different.

 

Ok so I had it up on my hoist today and it all looks pretty clean. I don't see any leaks anywhere from the exhaust.

so the codes 0420 and 0430 I have are bank 1 and 2 o2 sensors, so im going to change those out and clear the codes and see what happens, unless someone else has better advice for me....

 

The exhaust leaks won't be visible until you remove the heat shields off the Y-pipe and block the exhaust tips while the engine is running. Even then, it might be a pinhole or hairline crack that is near invisible, yet this will cause P0420 and/or P0430. Also possible that the gasket at the front has a very small leak. This has happened on numerous LS430s across the world, just Google LS430 P0430.

Also, these 2 codes are for catalyst low efficiency, not for O2 sensors. These catalyst readings are a symptom of a leak - it is rather unlikely that your cats are defective.

I've said it here on a few other threads - all Canadian LS430 owners should remove their heat shields as soon as they own the car. The heat shields serve to accumulate salt water, which burns off, leaving salt permanently coating the Y-pipe and accelerating the rusting process. On top of that, the metal clamps that hold the heat shields on are made even worse, and if they are original from 2001-2006, they should be severely rusted by now.