So yeah got a triangle with an exclamation mark in it and some coil light, car is a 1.9tdi pd130 and the car won't engage in any gears; I'm basically coasting 1st to 5th to get around, sounds a bit more noisy too.
Not yet, ordered a new battery because I figured this may as well be swapped as the plug is under it (far as I know), for anyone else with this problem you can literally just leave the car to dry out (for a day or so) and it'll be fine again as the link said.
Edit: also by "for anyone else with this problem" I mean absolutely anyone with an Audi A4 b6 should chuck the plug as a preventative measure to make sure they don't encounter this, quite dangerous having the car go from motorway speeds to 40 with no throttle engagement and having to coast somewhere safe to leave it for a couple days.
Depends on where the water is coming in.
It can get in through the ECU seal or the bonnet pull cable grommet.
It’s not always the plenum blocking that causes the problem, generally you can hear the water sloshing about when cornering when it’s the plenum.