Direct answer
On the covered HP printer, 40 means the printer lost or received invalid network/data communication. Searched 2026-08-20: HP publishes its control-panel messages inside per-product troubleshooting pages that are rendered client-side and are not exposed as per-code URLs in HP's own sitemaps, so no HP page could be cited for this code specifically. Check it against your printer's own user guide. First, retry a printer configuration page and small local job.
Definition versus diagnosis
The display names a detected condition—not an automatically failed part.
What this covers
- HP printer covered by the cited source
- Displayed code or documented alias: 40
- The exact operating state described by the manufacturer
What it does not cover
- ×Another product type or original-manufacturer platform
- ×A visually similar but different code
- ×Internal live electrical, sealed-system, gas, battery-cell or control-board repair
Match every character and the exact product
ReversiblePhotograph the complete display and product label. This record covers 40 on HP inkjet and LaserJet printers; wording, numeric codes and customer-accessible recovery vary by exact product number and firmware.
Preserve the failure state
ReversibleRetry a printer configuration page and small local job. Record the operating stage, recent change and what still works before clearing the message.
Correct only the documented fault domain
ReversibleCorrect cable, network or print-server communication. Do not borrow a reset or meaning from a similar code, product or model year.
Verify once, then respect the service boundary
ReversibleRepeat only the shortest safe action that reaches the original stage. If 40 returns, stop repeated resets and use model-specific manufacturer support.
Evidence ledger
Sources behind this answer
Visible sources support the visible claims. Home Product Support records the publisher, the fact used and the review date; community reports can suggest an issue but do not become a published fact on their own.
Exact questions
Common follow-ups
What does 40 mean on a HP printer?+
The printer lost or received invalid network/data communication. Searched 2026-08-20: HP publishes its control-panel messages inside per-product troubleshooting pages that are rendered client-side and are not exposed as per-code URLs in HP's own sitemaps, so no HP page could be cited for this code specifically. Check it against your printer's own user guide.
Can I reset 40 without fixing the cause?+
A reset may hide the display temporarily but does not correct the documented fault. Record the code and complete only the safe checks first.
Why is the complete model number required?+
Manufacturers reuse characters across platforms. The model number determines which official table, controls and service boundary apply.
When should I stop?+
Stop for smoke, arcing, burning odor, uncontrolled water, gas odor, battery swelling, extreme heat or any condition the manufacturer directs to professional service.
Answer for the exact device and software version shown above.