Annoying P0430 need to solve it.

[2001LC]

Bummer!
Can you list every DTC (code) that has been pulled from your system. Going back as many years as you can, in order as they appeared?.

 

[LXroookie]

OP may just have a small issue. Maybe just defective O2 or has a Wonky A/F, etc.... We can hope!

Many things upstream stream can affect the CATs. Wonky A/F's & O2's certainly can give a bad reading. Gas cap, fuel pressure, fuel injectors, MAF, Vacuum leaks. Those pre head or exhaust issue that may result in both P0420 & P0430 at or about the same time. Most of those should give their own DTC, but sometimes just don't! Why! I suspected they just aren't quite out of spec. Those "near out of spec" issues can add up.

With just a P0430 or a P0420 only, we focus more on that bank. P0430 is bk 2, so we focused more on head to rear of O2 in bk 2. Like bk 2 Vacuum leak (intake gasket of Bk 2), fuel injectors & seals, spark plugs, coils, valves, head gasket, exhaust leaks.

In OP's case, he's mention coolant loss. It's very import to identify this before proceeding. Not only could this damage CAT, but the engine. The concerning statements is he "didn't find". Every coolant leak I've seen, can be found externally on engine with time. Some, like at head gasket that "are" external can be very hard to see. I inspect each side of engine with flash light and a mirror. I do this with all lower and upper covers off. In the VVT engine seeing head gasket under intake manifold is not possible, without a camera. I use a $40 drain snake camera hooked/Wifi to my iphone. Only one I can think of, that can't be seen, would be into a cylinder. I'm not saying this is PO issues. But must be determined as a first step.

Second issue PO stated, was ticking after warm up. This may just be the fuel injectors ticking. But if and exhaust leak needs identified and repaired.

Also unless one has a virgin 100 series, never touch by anyone's hands. We've may have old procedure repair errors (mess ups) to contended with also.

Getting all in proper working order first, is key to P0420 or P0430 not coming back.

I've heard some say you can tell if a CAT bad, by thumbing on it with a rubber mallet. If something rattle bouncing around in it, it's bad. Well, yes I suppose if CAT fell apart. How would it fall apart. Impact for one. It can also burn up from within and fall apart from raw fuel dump in CAT. But that rich a fuel condition and cylinder temp runs cool. Maybe one or two fuel injector pump in excessive fuel could do this. Sensor read as rich and leans fuel trim of that bank. Yet that or those bad fuel injects just keep dumping excessive fuel. Also excessive leak down of fuel injectors. Then we start and dump raw fuel in cylinder could also be issues, I suppose. Excessive leak down is generally associated with long crank time to start engine. This condition and others related to fuel injectors are more seen with low mile engine. Engines that sat long period of time without be started or used bad fuels with water. Watching fuel trims can be useful tool. There is also a way to shut down a fuel injector with Toyota Tech steam SST tool. Unfortunately we can't do (that I've seen) with a $20 miny VCI hook up to tech stream.

So I have the p0430 code and I’ve just had the truck back for a few weeks now. Previously was sitting for a few months. Wouldn’t start. Turns out fuel injector fuse was corroded. Mechanic put a new fuel injector fuse in. A week or so later the check engine light came on. My 2000 LX is now just under 140k miles. The crank time for starting it seems to have increased. When I drive it, it sounds and feels pretty smooth until I’m stopped at a light or intersection, or in reverse; while stopped and/or in reverse, there is a vibration that is very apparent. Sometimes it’s less apparent but mostly very. Do you think this might have some to do with the actual fuel injectors?

Note: I’m 3rd owner. (As of summer 22) previous owner used it to drive about 2hrs highway to and from work everyday. He lived in a small city outside Dayton, Ohio. I now live in Cincinnati,OH and it’s been all city driving with the use of highways when needed.


Any insight here??

 

[2001LC]

Probably was the EFI fuse, which was replaced. But that would not likely have anything to do with P0430 (BK2 CAT). It can be a wonky O2 sensor. But most times, the CAT is bad.

With a CAT failure, we need to look closely, for upstream possible issue. If not in flood or CAT has taken a bad impact.
Any exhaust leaks on PS side at or before CAT.
How's compression.
Any vacuum leaks.
Spark plugs & coils
Air filter.
How are the fuel trims (FT). I've been finding bad MAF sensors, damaging CATs. So often we do not get the MAF code. FT can be a clue to many things, including MAF.

Long crank to start. Is often excessive fuel injector leak down. When any engine sits long periods, it's tough on fuel injectors and fuel pressure regular.