1000 — no paper in the rear tray
This one means the rear tray is empty, the paper isn't seated properly, or something is in the tray that shouldn't be. Take everything out and look before you reload, because a stray receipt or a piece of packaging reads the same as a fault. Reload with the guides snug against the stack and the paper pushed down until it stops. If you're printing from the front cassette rather than the rear tray, check the printer isn't set to expect the other one.