+1 on adjust it yourself.
I just did a new ball joint end on the Pittman arm. Adjust it by leaving the pinch clamp loose, and driving a bit on as flat a road as possible (no crown), pulling over, tweaking the adjuster a few times in whichever direction is necessary (trial and error), I was able to get the wheel spot on. Took about 15 minutes.

Sorry, I realise that this is a bit of tail chasing, but when you went into Nano to manually switch on the compressor, did Nano report that compressor was already on? I am guessing it said off.
Next time it does this can you write down the status of pump, pressure switch, and over temp switch before you change anything?.

It could still be an intermittent pressure switch or, less likely, the temp sensor.
Although, I would think that if either of those were bad, the ECU would not allow the Nano to turn on the pump?
Of course, intermittent faults are a bugger to track down, which is why I am asking previously answered questions......Looking for you to catch a different reading.

If, when you switch on the pump with Nano, as you said, the suspension immediately begins to rise, and stays up, I am thinking that the compressor is fine.
Mine was doing much the same thing, and it was a faulty relay. It could be an intermittent connection on the PCB of the fuseboard as well. They do fail.

Hmmm....Don't park in Dorking?

Has anyone ever been able to get Collin and his merry men at BBS to tell us what an "Unknown Fault" is?
I get them whenever either of mine throws a wobbly. Clear them and all good again. It's nice that it tells us that there is a fault, but useless for diagnostics. What does RSW show these faults as?
As for somewhere else to look, Have you confirmed that the plugs on the EAS ECU are clean and tight?
All of the intermediate plugs that the sensor wires run through?

Since you have now had a 4 wheel fault, Is this yet another odd P-38 issue caused by a corroded or loose
earth point affecting the ECU? That could cause all four sensors to mis read.
Have you run through all of the earth points and cleaned them up? This, I have found is practically a basic service for these things and at 20+ years, and in your corrosive environment, could be due.
Bad earth point will cause all kinds of seemingly unrelated gremlins to randomly pop up (Like touch the brake and the radio goes off, and HVAC display blanks out)
Good hunting!

They like to lull you into a sense of false complacency, then strike! (usually on a dark and stormy night far from home)
It should be fine now until you forget to bring the Nano with you.........They know!

Seriously tho' That is an odd one, and I would like to know why they can heal themselves. I have experienced short periods of the same type you have been suffering, and upon closer examination, the issues have cleared up. No cause and effect!
Good luck!

Not such a bad idea. Good quality sensors are getting pretty thin on the ground.
At some point, probably soon, we are going to need something other than the horrid chinese parts.
In the meantime, I am buying any sensors I can get when I visit the breakers. Used OE beats pattern parts
any day for these things.
Just thinking a bit, a small plug to plug module to interface a hall effect sensor and output the voltages
a pot would do should not be too hard? May need to add a hot lead at each sensor to power it?
I agree, the ECU itself rarely gives issues.

Have you got a spare pressure switch you can swap in?

If it is getting down to solenoids acting or not, have you checked the connector to the driver pack beneath the valve block?
Apparently, the pins can become loose over the years causing all sorts of intermittent mischief!
Maybe, if available try a different driver pack?
My tendency is to suspect the pressure switch itself.....
My 02 has tossed an EAS error on the dash and when looking at the error on nano, it is telling me the switch has not changed state or something like that.
I clear the error, and it goes away for months or years......I do have a spare switch in the cubby just in case it is really dodgy, or finally fails.

Fiddled about a bit more in no particular order and pump started running for awhile without doing anything specific.

Fiddled with what, specifically?
Wires? connectors?
Or did you fiddle with nanocom only?
What got wiggled or jiggled?

It's ok to admit at this point that you gave it all a "gentle tap" with a 10 pound sledge hammer........

It could also be a dodgy connection on / in the fuse board.
Is there voltage actually present at the pump when the Nano says the pump is on?
That's how I finally determined I had an intermittent pump relay.
An issue in the fuse board will bring up all sorts of odd gremlins!

Don't forget the relay in the under bonnet fusebox.
I had been chasing my tail on an intermittent compressor issue for too long. Turns out the relay was acting like a thermal circuit breaker. New relay, no issues!

I believe I have this one solved.
I got a couple of pump kits and rebuilt and tested my 2 spares.
Put one in the HSK, and had the same issue.
Using a clamp on ammeter, I was watching the running current to be sure it was coming up to pressure
by observing current rise over time, and saw some odd dips in the current just before it would do a short cycle.
Turned out to be the relay, which in a bench test was heating up very slightly, and the contacts were
opening, cooling, and closing.
So, new relay, and all good!..................For now..............

I have an odd continuing problem with the EAS on the HSK.
The system works flawlessly, however, the compressor cycles on and off frequently.
Sometimes it is as little as a few seconds, sometimes it is on for minutes.
Nano reports that the compressor is indeed being commanded to switch on and off each time it does so.
Pressure switch remains at "Open" status and thermal switch reports as "Normal"
This condition persists whether it is first thing in the morning and all is cold, or after a long hot drive. Same behavior
Any ideas?
I have ordered a pump rebuild kit just in case, but I believe the compressor is fine.
Have a spare pressure switch as well, but as Nano reports that the switch state is unchanged, yet
commands the compressor on and off, I don't see that as probable cause..
I am baffled.

All of the P-38s I have owned (5 that were drivers) have had their Becms unlocked. No issues.
I have heard that one as well about unlocked causing issues. Have you ever heard just what these issues may be?

For the record, The Missus' HSK has never immobilised on me or my Missus.....
For that matter, I have only had 2 incidences of immobilisation on Bolt in 12 years, and I caused both of them.
I do have PsiDoc's emulator boards installed on both now as a belt and suspenders approach to P-38 ownership.
As you know, there are several places that will unlock a Becm, and some clever folks that have worked out how to
derive the fob code from the fob itself. I have just connected the dots as it were to derive a fob for the HSK by using a redundant fob from Bolt. Just saying, if you are determined enough, it can be done.
It is great that Les in Wales can do new fobs for us here in NAS land, but I do like the flip keys, and this cost me nothing to do.

Oh, I am aware of BBS service on the bar code, but this is about using a fob from one P-38 that you know
the code for on any other P-38. As long as it has been unlocked.

I was just getting a few old fobs I have accumulated over the years ready to send off to have their codes read.
The plan being to input a known fob code into the HSK's Becm and see if I can get a working fob for it.....
Going through the fob bin, I found I had an extra fob for Bolt making 3......The one in the bin said it was key 1.
This got me thinking I could test my theory before sending a parcel to the UK......
I have read somewhere that you can only change the first code number (not correct) so, I went into Bolt's (unlocked) Becm and read the 3 stored codes. The first one happened to be 64, so I went to the HSK to input that into it's (also Unlocked) Becm. I found that the first number in the HSKs Becm was already 64......Caused me to recall I had tried this about 2 years ago without success.....
However, being a bit tenacious about this sort of thing, and seeing as I had no working fob for the HSK, I went ahead and loaded all 3 codes from Bolt into the HSK....What could possibly go wrong??
In this case, nothing went wrong, and the Becm accepted all 3 codes. Figuring one had to be correct, I tried to sync the fob.....
It WORKED!!.
I pulled the key from the non working fob that came with the HSK and inserted it into the now working fob.
As this is the Missus' daily driver, I am now a hero in her books!
I am going to send the other 2 fobs off to be read as they work, but I have no way of getting the codes for them.

This means, of course that if you have a fob on the correct band, a Nano or equivalent, an unlocked Becm, and a way to get the fob code, you can very easily make any fob work! Even the ones that they sell on sleezebay!!
Now for a large celebratory Rum!
Cheers!

It seems, from looking at my fleet, that early 99 and prior years do not have a sensor at the bottom of the radiator for SAI, but late 99 and up do have this sensor.
Yours being a 2001 will indeed have this one. I had an issue with a dirty connection at said sensor on one of mine. A quick clean took care of it.

"For some rough figures, charging a battery and driving and electric motor from your electricity is around 90% efficient."

That would be a ~very~ rough figure. Let's look at the "Rest of the story"......
What I have yet to see is a good analysis of the calculable, known losses in power generation and distribution.
Here is a quick and dirty one of my own:
If we start with a natural gas fired power plant, and 100 cu litres of CNG.
Burn that in a furnace to boil water in a heat exchanger, make steam, turn the turbine to generate electricity.
Best case is 60% efficiency and only if you can use the waste heat to do something. (as low as 33%)
https://energyeducation.ca/encyclopedia/Natural_gas_power_plant
So, 40 of our Cu litres gone to heat at the plant.
Now we have electricity at about 500kv which has been stepped up there using transformers.
These are pretty good, however we go through no fewer than 4 to go from the plant to the rural grid, to the local grid and to your house. we will through in transmission losses here as well so lets call that 10%, but it can be much higher.......So, kiss off some more CNG..
https://blog.se.com/energy-management-energy-efficiency/2013/03/25/how-big-are-power-line-losses/
Now, we have a battery charger coming in at about 80% on average, so more heat and more wasted energy.

Batteries themselves are not 100% efficient and degrade as they are cycled, so average over a 6 year life cycle? call it 80% with 20 % being turned to heat in the battery.
Electric motor and controller? 90% is generous, so another 10% loss to heat.
I have used the average losses here and leaned toward very conservative numbers.
Even so, you are kissing off more than 50% of the electrical energy produced at the plant before
it even sees the EV. other types of plant, like coal are far less efficient.
Not my idea of an environmentally friendly solution.
Question for LPGC: How much better would it be to just burn the CNG in a converted vehicle?
The other issue for EV's quick adoption is, of course, the grid itself. On my Easter trip down to So Cal this year, I was chatting with an old friend who lives in a relatively new (late 90's) high end sub division in Irvine, California.
Many of his neighbors went out and bought Teslas early on as they are a status symbol in So Cal.....
Think Chelsea Tractor!
Well, the main power transformer feeding this subdivision has caught fire and been destroyed Twice in the last year!
Cannot handle the battery charger load. Not just the additional power being drawn, but the power factor issues.(Grids hate reactive loads like chargers, they love resistor type loads like bar heaters)
Feel free to tromp on my numbers, as I said, this is rough.......PETROL RULES!!!!

With all of those seemingly unrelated things going on, a possible common cause would be a bad ground.
There is one under the climate control, and if I recall, another under the dash on drivers side.
All grounds on a P-38 MUST be clean and tight. Just giving them a wiggle is not enough. Remove, wire brush
re tighten. A bad ground causes current to flow from one circuit to another rather than to the proper return path.
Probably more likely to be the one under HVAC.
Fuse board is another suspect. Can she remove the cover and have a sniff for the smell of burnt electrics?
My bet is on bad ground though. Have a look at RAVE which will show you what circuits share the ground points.
I am away from my computer that runs RAVE, but Gilbert has them memorized! I am sure he will chime in when he wakes up.

Can't tell you the part number, but if needed, you should get a genuine Bosch. Gems does not seem
to mind pattern parts, but Thor will generally run like crap with a copy.
Be aware that there are a LOT of counterfeit Chinese Bosch parts floating around.
A genuine part will have a holographic sticker on the box with a unique code number.
Take that code number to the Bosch parts checker.
https://protect.bosch.com/
Enter the code, and see if you got a good one! Just having the sticker is not enough.......
They are counterfeiting those as well!
Yes, they are indeed stupid expensive!
Happy hunting.

You posted as I was writing.....
I think you are on the right track though.
Interestingly, My 99 does not have the additional temp sensor, whereas my 02 does.
Even though the 99 was manufactured in Sept? Hmmmmm??

Gilbert, Good point.....
Is the SAI system actually switching on when this happens?? If so, it is certainly
the problem. (now we need a solution!)
If it is not activating when warm, obviously it cannot be causing the problem?

I have never been aware of the system coming on after a cold start, and there is indeed a second temp sensor at the bottom of the Radiator for 99-02 Bosch systems. Possibly if this sensor is faulty, or has a bad connection, it could cause the SAI to erroneously activate?

Those are interesting projects.
I know there are more than a few folks out here that would love to see an updated Becm.
Welcome to the pub!