DIAGNOSIS The printer cannot read the chip on one or more cartridges. Causes are dirty electrical contacts in the printer or a defective new cartridge.
FIX 1. Turn printer off. 2. Remove all four toner cartridges. 3. Locate the set of six thin, gold-colored electrical contacts at the back of each cartridge slot. 4. Gently clean these contacts with a dry cotton swab. 5. Reinsert each cartridge firmly until it clicks. Power on.
IF THAT DIDN'T WORK Reinsert the cartridges one at a time, powering the printer on after each. This will identify the specific slot or cartridge causing the communication failure.
HEADS UP The cartridges must be genuine HP. Even new third-party cartridges can fail this handshake immediately. Ensure you remove all shipping tapes.