DIAGNOSIS The printer's smart chip isn't reading the new cartridge. This is almost always a contact issue, not a bad cartridge. Dust or a previous cartridge's plastic shipping clip can block the contacts.
FIX Power off the printer. Open the front door and remove the toner cartridge. Look inside the printer at the back of the toner slot. You'll see a set of small, gold-colored electrical contacts. Use a dry cotton swab to gently wipe them clean. Reinsert the toner cartridge firmly until it clicks. Close the door and power on.
IF THAT DIDN'T WORK Remove the cartridge again. Check for and remove any orange or green plastic shipping locks or tapes you might have missed. Fully seat the cartridge. If the error remains, try the original cartridge. If that works, the new cartridge's chip is defective.
HEADS UP Never touch the printer's internal contacts or the cartridge's green drum with your fingers. Oils cause permanent print defects. Only use HP 18X (CF218A) or certified compatible cartridges for this model.