Hello!
I have a Volvo C70, 2009, 2.0d 4 cylinder, PSA engine + FAP fluid (ADM tank), +DPF 110,000 km.
Sometimes after 2-5 thousand km the entire ADM tank content "disappears". Based on the cleaning of the DPF filter: pump it into the fuel tank, because the filter is yellowish brown when cleaned (removed, when washed with chemicals)
The tank is not leaky, there is no tuning on the car, there was a software update, the ADM module under the rear seat was replaced, the FAP fluid tank was replaced with a pump, the DPF filter was cleaned with chemicals 3x, the tank cap was also replaced.
Codes:
ECM-2585 Additive dosing module (ADM). Faulty signal
ADM-0002 Level sensor, additive. Bad signal
These occur because the refill-reset -> calculation says that there should still be fluid in the FAP tank, but the sensor shows an empty tank. (the sensor only sees in the tank that the tank is empty (I opened it, looked))

I have already filled it with 1 liter 4x (I reset the counter in ViDA, but it always pumps it out.

Does anyone have a tip why it unexpectedly pumps all the FAP fluid from the tank into the fuel tank?