80.0022 EIO error in Hp LaserJet

I have An old Hp LaserJet 2420n printer that worked fine until a “80.0022 EIO 0” error showed up.

On the manual this error should implement that a critical error of the EIO accesory card has encounterd. But my printer has not an EIO card. The slot is empty.

I used to connect the printer by ethernet cable...

Do you have any idea how I can fix this?

Thanks in advance,