981uz

Hello everyone,
The code is: P0430
My engine light has come on my LS400 1998, its code that its throwing is bad cat on bank 2. This isn't a terrible problem as the car has an exhaust leak I've been putting off anyway. The question is clearly I can try and find an OEM cat but i would really like to use the magniflow cats listed in the link below. Can someone tell me if this is a good idea I've always wanted the car to be a tad louder. And obviously I would replace both cats with the magniflow.

https://www.summitracing.com/parts/m...us/model/ls400

Scraape

I have a 98 as well, with the p0430 code as well, and sometimes your cat isn't actually bad after all. A downstream o2 sensor could be malfunctioning, and an exhaust leak or vacuum leak can throw stuff off as well. Also clean your air mix path on the throttle body.

But to answer your question i'm sure you could use the magnaflow cats and get them welded on or whatever

paulo57509

Definitely fix the exhaust leak and see if the DTC goes away.

The DTC you're getting is for converter efficiency. The ECU compares the upstream and downstream O2 sensors. If it's out of range, it'll set a DTC. depending on where the leak is located, it can contribute to the out of range condition.

It could also be an O2 sensor as previously mentioned.

Banshee365

I am struggling with intermittent P0420 and P0430 codes. They alternate back and forth but set every 100 miles or so. I don't have any exhaust leaks that I know of but feel my fuel economy is a bit below what my experience with LS400's has been. I am curious if a rich mixture from another issue is overpowering the cats and causing the downstream sensors to see a bouncy wave rather than the mostly flat line that they want to see. I have had this issue with different ECM's and different upstream and downstream o2 sensors from different cars as I've put this car together from parts. The problem has followed the engine, engine harness, MAF sensor, and cats. I have another mid-pipe exhaust section with cats so I may try those just for grins since it's free. The ECM's ECT sensor is OEM new so at this point I'm thinking the MAF may be reading a little off causing the car to run rich or the cats are actually bad. The inside of the cats sure looked great the last time I had them off though.

I'm not hijacking your thread as I'm dealing with the same issue and wanted to put my thoughts out there on what I'm going to go after on my car. Usually those codes are from a leak at the front of rear of the cats, usually the rear.

981uz

So as you guys have advised I am going to fix the exhaust leak first and so if that takes care of the light. My only question which is probably a dumb one is; I'm taking it it to my usual shop and will the code need to be cleared? If so will the code be able to come back if this method doesn't work. Thanks guys for the advice I do truly appreciate it!

Banshee365

Yes, if the code is cleared it will certainly come back if the code setting parameters are met.

sha4000

iTrader: (1)

Lots of ppl get these codes if there is a leak at the flanges. I just put exhaust paste around the flange and it goes away for a while.