Dbo wrote:the first two long flashes are to say the ecu is ready

gone into diagnostic mode
That's not what the manual says though Dbo?
It says one blink when you turn the ignition on and then shows the codes.
When I've got codes out of my 2, that's exactly what it's done.
They've never given me 2 blinks to say it's ready, so have never diagnosed it as reading code 20 at the beginning and they've never given me code 20 in amongst any of the other codes.
The rapid blinking you then see Bludge, is it switching between codes in the main ECU and sub ECU.
I'd interpret your code reading as 20, too.
There's a long winded test procedure for code 20, because it could be a large number of things as well as just the main steering sensor (one of the other things being the ECU lol).
Curious co-incidence we've had 2 ECU's giving that code this week though!
PM coming your way ref ECU.