Thanks a lot, it is very useful. It raises few questions though.
I see urea temperature 0C (see some earlier posts with a similar case). Still the heating is not switched on (heating power 0%). This made me think that the urea temperature never goes above 0C (just like the pressure never goes below 4bar being the end of sensor range) and therefore seeing 0C is not an error and the "authorization by temp" is linked to another temperature. Now, that you saw 8C urea temperature, it clearly shows 0C being an error.
Also strange when I start the engine, the Authorization by temperature is NO, and later (without starting the urea heating and without changing the 0C measured temperature) it turns AUTHORIZED. So, which input can be used for this and what is the threshold?
If the Authorization by pressure is indeed the liquid pressure, then why doesn't it start the pump? It says "pump is stopped". It does not say "failure" and when I tried the small motor on it, it ran happily. I would understand if I saw, that the Pump is On, the pressure is not going up above the range-minimum 4bar and it reports a failure.
Also, I am not 100% sure, but it seemed to me, that when the Authorization by temp turned On, immediately then the P20E8 came up. With the logic you described, I would assume, that it cannot start the pump until the temperature is OK and then it gives some time for the pump (it is a rather small pump with the buffer tank) to build up the pressure. but then again, the pump remains in stopped status and the error comes immediately.
Is there a chance that you can measure the normal sequence of events with a cold, starting engine? E.g. when is the Auth by pressure turned ON, what temperatures (urea, cat) you see when Auth by temp turns on, when do you see the Gauge Pump not in stopped phase, etc. Thanks.