Set CWCS to 1 so it reads the PWM-signal instead of trying to find it from CAN.
That will read the signal via the PWM wire going to the ECU (I hope it is?).
P1606 - I never had that issue when fitting 551K to a 551C car.
Which loom are you using in the car?
You should be getting fault codes for the 2nd camshaft adjuster.
Do I have the PWM signal, I dont think there is wiring for it in the circuit diagram? But it's no problem testing with different CWCS.
I've just replaced the ABS unit with a used one since my old gave up completly.
First I thought that the new one was faulty but I've tried starting the car with my old C-box and then I don't get P1606.
I've modified my stock loom according to the differences to the the RS4 loom I figured out. Second camshaft adjuster, solenoids for air box and SAI and som changes to +12v feed to some parts.