Inner Cover error on Canon PIXMA ip4300 printer

This is a "Sensor" issue, there is a sensor that detects when the Cover is closed, this is either faulty, not being activated, or being activated but not registering at the CPU. Sometimes it is an actual switch, others it is a hall effect sensor, optical, magnetic sensor or the like. Have a squiz and see if ya can see any sensor etc. maybe its blocked etc. Otherwise I think it's gonna have to go 4 repair.. If so get a firm "Quote" B4 allowing them to proceede.