Progress indeed! So my guess is that indeed there is a leak at the reservoir. My guess is the fault happened after raising everything up and it switches to fill the reservoir. With the struts closed off and the reservoir closed off there is very little volume for the air to go. So the PSI climbs way too fast and it will create that fault code.

The fact that the compressor raised things tends to make me think it is also not an issue at this point. 145 is a decent PSI to at least raise things, but when switching to reservoir it will want to get to over 200psi. Swap the reservoir and it may be good to go for a while!

 

thank you so much for your help. Nice to see some progress here.
Think any ol tank online will work? Or is oem best?

 

I think OEM is the only option but I would not hesitate to get a used one with an easy return policy. If you get used, get the most recent year you can find. Some seller have "new" ones listed for cheap but if you look close you can see they are used and been painted. No clue how much a new one costs. And while not ideal, you can drive it like this. Just make certain your valve block you used for a line cap is secured. I would avoid height changes and any you make in an upwards direction will be slow without the reservoir. But there should be no danger in taking on the road.