...however it has an aftermarket head unit, not sure of make but suspect Chinese Android. Have been told the front and rear parking sensors don't work, and have been advised it's down to the head unit can bus etc. What OEM head unit, ideally refurbished, should I be looking for to ideally cure the parking sensors issue, ideally with built in SatNav, DAB or should I go for a Pioneer unit, for instance, or will it nor cure the parking sensors issue? Thanks in advance...

Your first mistake probably is to believe the seller when he says the parking sensors not working is a fault with the head unit, they may well have failed of their own accord.

 

It could be that the particular head unit does not display parking sensor info, the one I fitted to my 2006 Octavia didn't but the audible warning tone (which gets progressively more insistent the closer you get to an obstruction) carried on as before, TBH the stock display was pretty useless anyway and I never used it or would accept what it said as gospel.

 

Nobody here can tell you what head unit will fix the problem if that is not actually what the problem is, the parking sensor system is fragile enough without any help and the head unit if compatible is simply displaying info taken from the canbus communications from the parking sensor module if it is working correctly.

 

I don't have parking sensors on my current Yeti, with a reversing camera I don't feel the need for them, £10 spent on a reversing camera which will almost certainly be compatible with the head unit you have would be money well spent rather than spaffing away hundreds on another head unit to not fix a fault with the parking sensors.

 

Maybe things are different on a 2009 Octavia, others will say if the above is incorrect for your vehicle.

Thanks, J.R., though the seller didn't tell me that, it came from a subsequent discussion with someone completely separate. Appreciate the advice, will find out more when I pick the car up.