Designjet T520 false paper jam error

[designjethelp]

1. Printer Powers up.
2. The blue screen lights up with the HP logo, printer initializes.
3. While the carriage moves from one side to the other, another message comes up that is Insert sheet of plain white paper and press OK.
4. The carriage starts on right side and moves to left and goes back to the right side.
5. After returning to the right side the message appears on the screen:
The printer cartridge cannot move. Open the ink cartridge door, clear any paper jam or obstruction and touch OK.

What is causing the false paper jam error message?

[Ouccema]

Hello,

first of all, try to check the SVS side: if any jammed paper stuck

Clear the encoder strip  / the line sensor with dry-wipe

Run the carriage servo test from the Support Menu