e90 0468 ISTA could 3 Charge Pressure Sensors be faulty

[Colink2]

Symptoms after clearing 0468 error it returns 1 to 3 days later
Yellow dash warning appears 2 to 4 days later but often goes out by itself then back on again a few days later.

General question - Are Charge Pressure Sensors so unreliable that original + 2 X used ones are faulty? (Not tried a new one yet)

I need help to understand what I am doing wrong using ISTA. I am obviously missing something obvious.

If after listing errors I clear the faults I cannot find a way to go through the test procedure to check the air mass system

So I leave the errors in place and these are the steps I go through with ISTA:

IMAGE1 
ISTA tells me I have to eliminate the error before continuing - but how do I eliminate the error before ISTA tells me what is wrong?
If it just means clear the error - how do I clear the error before leaving the test procedure or if I start by clearing the error how do I get to the test procedure?

IMAGE2 
I am now continuing the test procedure - am I wasting my time because I have not "eliminated the error"
I am then asked to switch on Terminal 15. I have searched online, found lots about Terminal 15 but not clear what to do at this stage.
I pretend it is switched on and continue the test  - Am I wasting my time?

IMAGE3 
After operating throttle valve the charging pressure rose by Zero mbar

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"Replace Charge Pressure Sensor" - does this have any validity (based on comments above)?
I purchased a used Charge Pressure Sensor. It had slightly rough idle and returned same fault pattern as original
Supplier supplied a second one - no rough idle. It worked for much longer than previous sensors - 7 days before yellow light, light cleared after less than one day.

Note both of the above were cleaned with electrical contact cleaner

I have no problem paying for a new one, but would be disappointed if I ended up with the same error due to my incorrect user of ISTA

4 min video of my use if ISTA here https://youtu.be/qYciQ1cPuUs

Any comments, or recommendations welcome

ColinK2