If you own a HP Designjet 500\510\800 printer, there is an issue with new printheads.
Part numbers impacted: Black C4810A, Cyan C4811A, Magenta C4812A, Yellow C4813A
If you replace an old printhead with a new HP brand, you will get a 'Faulty printhead' message on new printhead installation.
HP new printheads with an expiration date of March 2020 or later are not working. I've also heard HP is discounting production of printheads all together at the start of 2019.
While HP is working on a firmware remedy, the new Chinese brand I offer will continue to produce reliable consumables into the future.
The Designjet 500/510/800 series plotters are the best HP ever made in wide format printing.
If I can be of any assistance in servicing your printer, please contact me, Tom at designjetpartsfast.com