The reason as to why it works at idle but not at highway speed is another indication that cats may be plugged.
The higher the speed, the more backpressure from a plugged cat.
You will see that when trying to accelerate uphill at low speed but higher RPM. You should feel "bogging".

The huge engine back pressure confuses the computer, and can show things such as bad MAF sensor (Mixture), timing, misfires (thinks it could be due to valves, cam, etc.) and other things.

I found my old invoice.
Mine threw P0101, P0102, P0300, P0175, etc.
Was showing 9psi at 3400RPM on bank #2 at the front O2 sensor. Way too high due to plugged cat on that side.

Problem with the H2 is that it uses technology which is old as dirt now. 20-years old. The codes are confusing, and do not always make sense as they can point to things which are not the actual problem.
It is not refined like newer vehicles are.

Let me know what you find.

 

Hi finall,
I think you have figured out my problem! I did a temp test on the cats, I don't know how accurate it is, but I measured the temp at the O2 sensor going in and going out of each cat. driver side was within a few degrees on the inlet/ outlet. the passenger side was 100F cooler on the outlet side. I think I have a blocked cat.
this makes sense as to why I got all the other codes with maf, camshaft, etc sensors. I have the P0106, P0011, P0016, P0420, P0430, Mine was feeling like it was bogging down and then it would stall, especially at highway speed. then once the cat cooled off then it would start up, otherwise the engine would not start.
Looks like I need new cats. I'll let you know once I get that fixed.

Thanks so much for your help!!
Steve

 

Glad to have helped! Doing with temperature instead of pressure was a great idea, something I did not think of.

Mine was the right side. Which side is it on yours?

 

Having similar issue and curious if this worked?

 

I once saw a youtube by Scotty Kilmer on how to fix a blocked cat by adding a gallon of Laquer Thinner to 1/2 tank of gas and then driving up on the highway about 150 or so miles and this cleans them out.

I have not had an issue to try it but if it worked it would save a small fortune for the cost of a replacement cat and the installation. Perhaps someone who may have done it here can chime in....

 

Lacquer thinner dissolves shellac.
This is an old trick to clean out blocked injectors.

Not cats. There is nothing left after the solvent is burned in the engine to dissolve the crud that blocked the cats. Do you know any different? Did they say how this could possibly work, chemical explanation?

I could buy it if they stated they took an old cat and bathed it in solvent.

 

There's a number of youtubes on doing this including Scotty Kilmers one. Who knows it might not work at all but I think a $12 dollar gamble is worth it when you consider the cost of cats and the installation costs.

Check out the Youtube: