hello guys, i have a problem with an A4. the car in the electronic engine diagnosis no longer shows any errors, not even in the SRC system, but the display shows adblue + spanner +400km (attention NOT adblue tank symbol).

I have proceeded with descaling the adblue injector with lukewarm demineralised water. I have emptied the two adblue tanks (total approx. 20l additive), cleaned the pump and level (always lukewarm water and demineralised). I have refilled with add but the warning light continues to appear. it should be a fault (I think) but after making the diagnosis (with MM with Texa and also with BrainBee) nothing is indicated:(

I had made the diagnosis with error P204F when it had 1000 km of autonomy, but after deletion it no longer appeared

if anyone has any suggestions .....