today i was able to solve the "low oil pressure message" on my car.
Since i've read many and many articles and watched videos about this subject without finding a solution, let me tell you what happened in my case.
Off course when the problem first started, i've looked on internet as many does, and found every possible solution. Lexia was showing errors like P0012, P0011, P0010 and off course "low oil pressure".
I've checked the VVT Solenoid valve, which was perfect, changed oil, checked and changed the pressure switch (since it was cheap), and i was about to remove the sump to check the screen when we decided first to check again if the camshaft was in sync with the crankshaft.
It was at this point that we noticed that the screw that fix the accessory pulley over the timing belt pinion was loose ! I don't know how that has happened but it was partially loose, so the timing belt was free to move because the little pinion is free to rotate inside the key hole. This caused a malfunction of the oil pump (which is fixed on the crankshaft) and maybe to the alternator too, since i had many absurd electronic issues (like ESP warnings, temperature warnings, and so on)
So we put the sync pins to adjust the correct timing, removed the big screw, cleaned the hole and the screw thread , and re-mounted again with a little more of the suggested torque (for safety).
Immediately the car sound was way better, and no more "low oil pressure" warning, no more ecu errors, and the car feel even more powerful ! I've made now 300km without any issue.
I'm very happy that i didn't needed to buy a new car, and now i can aim for the 300'000km target
I hope that this information can help someone in my same situation, in the future.
Best regards
Dave