What does a flashing E followed by flashing O mean on HP Envy Pro 6455?

[Traveler2023]

Can’t print. Flashing E and O on HP Envy Pro 6455 printer

[Raj2111]

@Traveler2023 

Welcome to the HP support community.

I understand that your HP envy printer is  Flashing E and O , I am glad to assist you.

This condition occurs when at least one ink cartridge needs attention, is faulty, incorrect, missing, damaged, or incompatible. Reseat both ink cartridges, clean the ink cartridge contacts, restart the printer, and replace one or both ink cartridges if necessary.

Let's perform a power drain: 

• With the printer turned on, disconnect the power cord from the rear of the printer and also unplug the power cord from the wall outlet.
• Remove USB cable, if present.
• Wait for 2-3 minutes, press and hold the power button on your printer for about 30 seconds to remove any additional charge.
• Now plug back the power cable straight to a wall outlet without any surge protector or an extension cord (This is important) and then plug back the power cord to the printer.
• Turn on the printer and wait till warm-up period finishes and the printer is idle

Update the printer firmware 

• Click here to download and install the latest printer firmware from your product
• Click here to know different methods of updating printer firmware.

Perform the steps mentioned in this document - Ink cartridge errors

Insert one ink cartridge at a time to identify the defective ink cartridge.

Also, make sure the input tray is properly installed, refer to - Replacing Input Tray

Check for any jams inside the printer - E4 (Paper jam) error

Make sure the printer carriage is moving freely. 

Please perform these steps and Feel free to reply to your public post for any further assistance.

Thank you for being a Valuable Member of our HP Family.

-Regards,