The link below will provide you with all the necessary information to fix issues related to the HP Laserjet 2420 PrinterHP Laserjet Troubleshooting
Also, try the steps below.
1. Turn the printer off, and turn it on again.
2. Force a calibration by selecting CALIBRATE NOW from the Print Quality Menu.
1. Press example (Select) to enter the MENUS.
2. Press example (Down Arrow) to highlight CONFIGURE DEVICE.
3. Press example (Select) to select CONFIGURE DEVICE.
4. Press example (Down Arrow) to highlight PRINT QUALITY.
5. Press example (Select) to select PRINT QUALITY.
6. Press example (Down Arrow) to highlight CALIBRATE NOW.
7. Press example (Select) to select CALIBRATE NOW.
8. Wait for the printer to calibrate.
3. Perform a cold reset on the printer.
1. Turn the printer on.
2. Watch the control panel.
3. When the memory starts counting, press and hold the green example (Select) button.
4. Continue holding the green example (Select) button until the Ready,
Data, and Attention lights flash once, and then stay on steady.
5. Release the check button when the Ready, Data, and Attention light are
on steady. The control panel will display SELECT LANGUAGE.
6. Press example (Down Arrow) button once. The control panel will display COLD RESET.
7. Press example (Select). The printer will perform a cold reset and then continue its power-on sequence.
If this issue persists, contact an HP-authorized service or support provider. ( 1-800-474-6836 )
If the Toner is newly purchased and it is because of faulty toner, HP will replace it for no charges.
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