Can you keep using it?
Can you keep using it?
Contact customer support if any of these apply
- !31.40 remains after reseating a genuine toner cartridge.
- !The printer repeatedly loses cartridge recognition after restart.
What to check first
Step-by-step checks
- 1
Consumable check
Remove and reinstall the toner cartridge carefully.
Start with the official recovery step before moving on to parts or deeper servicing.
- 2
Consumable check
Confirm the cartridge is a genuine Lexmark supply.
- 3
Safe first step
Check printer date, time, and firmware if the message returns.
Background
What this message usually means
Lexmark uses 31.40 when the installed toner cartridge is missing or unresponsive. On this office mono family, the usual first checks are genuine-supply verification, careful reseating, and then date, time, and firmware checks if the message persists.
Before the message
What users usually notice first
Messages like this often appear after the printer fails one of its normal startup, supply, or paper-path checks and cannot return to ready state cleanly.
Diagnosis
Likely causes
The toner cartridge is not fully seated.
A non-genuine or defective cartridge is not responding.
Firmware or printer date and time state is contributing to the supply check.
Service
When service or replacement is more likely
- -This is a supply-recognition problem, not a paper-path jam.
Avoid wrong turns
Common misreads of this message
- -Treating the message like a confirmed failed part instead of a support clue about which system has stopped the printer.
- -Assuming any supply-related wording means the next step is automatically to buy a cartridge, toner, drum, or printhead.
- -Assuming no physical path issue exists just because no full sheet is visible at first glance.
See also
Related codes in this family
Explore more
More Lexmark printer families
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Helpful guides for this problem
Boundary
When to stop troubleshooting and move to support
Use the message once to classify the problem, then move to support if the printer still cannot return to ready after the first safe checks.
Keep browsing
Where to go next
Source notes
Lexmark's official 31.4x guide says 31.40 is a missing or unresponsive toner-cartridge error and recommends genuine-supply checks, reseating, and firmware review.
Built around official Lexmark user-guide and service-manual material for the MX431 and closely related mono office models. Exact code behavior can vary a little by print-only versus MFP model and installed options, but the main paper-jam and supply messages stay close across the family.
Printer error codes can vary a little by firmware, region, and exact model variant. Use this guide as a family-level starting point and stop if the next step would require disassembly or service-mode changes.
Known family variants: MX431adn, MX431adw, MS431dn, MS431dw, XM1342
Last reviewed: 2026-04-12
Reference: Open reference