I need some help fron the electrical smart guys.
The issues, going down the road at most any speed, the engine will shut off like turning a light off-on, quickly. Sometimes 3-4 times in a row with about 4 seconds between. It could go a day or more and not do it.
The latest issue associated with this is the instrument cluster, odometer goes out and says, no bus, all the gauges and speedo goes to zero like when the key is off, engine still runs, this will fluctuate a couple times too. Sometimes just the speedo stops but other gauges don't
Codes show 0420 and 1495. I found this by cycling the key on-off three times (shows in the odometer spot)
Is a buss just a wirring junction?
Previous owner must have had this problem too, he changed PCM and replaced all three connectors and spliced in the wires going to the PCM.
There are other things I want to ask but these first. Any help will be great.

what year, what make, what model, what engine, what transmission.

2001 Ram Van 5.9 auto
And the "no bus" doesn't stay on, only sometimes when gauges go haywire. Majority of this started after replacing plugs and wires.
188,000 miles. I've had the van for 3,000 miles
I keep remembering pertinent stuff.

If you are old enough to remember phones that had a party line, the bus is sort of like that. All the various modules use this buss to talk, each having it's own unique ID (kinda like your "ring" on a party line). Bus issues means something is not talking.

https://repairpal.com/no-bus-message-in-odometer-154

I would start by disconnecting the battery, unplugging the ECM connector inspecting it and using contact cleaner clean both sides of the connection, pins and sockets. Then reconnect, hook up the battery and see if it will start.

If not then I'd follow the link above.

That particular link has nothing to do with my issue, engine has no problem starting and running.
I'll weld in a new cat tommorow along with the two 02 senders. Then go over all connectors especially behind cluster, maybe a new circuit board. Check injectors too.

one area to look closely at, is the wiring harness close to the battery itself, and where it connects to the underhood fuse junction block. i have seen countless mopars [cars and trucks alike] from MY 1986 up, that has had wiring go bad from the battery outgassing, causing the insulation to break down, therefor causing the wire itself to wick the greenish corrosion found on your battery terminals into the wire for some distance, as well as cause breaks [corroded completely] at the corrosion site. i also have several PDB's on the shelf [for parts], with this problem. some [most] times it's hard to see, and you might have to really move the [suspect] wires around a lot to spot insulation breaches and "green" wires. this problem causes a LOT of weird, hard to figure out, problems. this has led to a lot of my hair loss ........

I will look into that. Now, update on engine issues, cut the cat off to replace with a universal one, wow, totally nothing inside, just a large chamber. A few shiny particles laying in the bottom. That's bound to be throwing the pcm-02 sensors off. Might buy both. Took a few starts to get engine to stay running.