To give a final update for anyone else looking at this issue, at the end of Dec, a local VAG specialist agreed with the P06DA00 error code being a possible cause. They checked the battery health and was fine. The seller agreed to cover the cost of a new engine oil pressure valve and the local garage carried out the work. That seemed to work for around a month until the end of Jan, when it again went into limp mode. Turning the car on and off would sometimes clear the code but not consistently. I also experienced the gearbox juddering while shifting between 2nd-3rd and 3rd-4th, as well as it outright stalling while coasting at 30mph. After more back and forth with the seller and the local Skoda main dealer, debating whether they had exercised their right to repair or not, we determined it was likely the camshaft or crankshaft speed sensor, which the camshaft sensor fault present in the original diagnostics as P072600 and P032200. The seller eventually agreed to collect the car and they replaced the crankshaft speed sensor, assuring me it was definitely this and not the camshaft. I had the car back after about 2 weeks. Test driving it, the issue seemed to be resolved, with lots of odd driving on steep hills etc to try and get any of the previous symptoms resolved. And then 4 days after having it back, while reversing onto my drive, the steering wheel goes click and the dash throws a driver's airbag error and all the steering controls are non-functional. I say enough is enough at this point and luckily they agree to have the car back in exchange for a refund. We did have a quibble over the fair usage deduction, with him trying to charge 45p/mile. I pointed out all the hassle we'd been through, that a chunk of the mileage was them collecting/returning the car, and that trading standards had a recommended framework (which you can see here) which should've been around 17p/mile. We eventually compromised on 26p/mile and after 5 weeks (not the 2 promised) I get the money back. In hindsight, I think my risk appetite was a lot less than I thought. But luckily enough a L&K 190 has just popped up for sale 5 miles away so fingers crossed!