I have experience sudden onset resistance / loss of PAS several times in the past few weeks. It always happens when turning left into my driveway, or when entering left into a roundabout or turning left exiting a roundabout. The sensation is that there is a sudden and quite definite loss of PAS as the steering suddenly becomes very heavy... and then just suddenly after a several seconds, the problem clears. Today my wife and I also heard a dull thud or whatever when it cleared. Any advice welcomed.

Cheapest first action IMO will be to try bleeding system with some fresh oil. After that you are into more serious money.

Way to bleed is on the site via search.

Of course one assumes the pump drive belt is OK and not being effected by a something like an engine mount being stuffed and moving as you turn left.

Miles ? FL2 MY10 TD4 GS traded in at 2 years
FL2 MY13 TD4 GS Current

46k miles
Behaves really well in all other aspects, it's just thus annoying random issue.
It never happens turning right... never happens under normal driving conditions, only when having slowed down to 3rd or 2nd gear when about to make a slow left turn... not so slow that the revs are at their lowest.

I'll check the points raised in the morning. Cheers.

It might be worth changing the reservoir too. It has the filter built into it. Maybe some trapped sludge is shifting to one side when you turn left? Past: FL2 TD4 HSE Auto
Evoque SD4 Dynamic Lux Auto
Present: Audi A3 S Line.