Error code 7F is displayed when my printer is working

Problem

Error code 7F is displayed when the printer is working.

Cause

The printer has detected that the toner has run out.

Solution

1. Use the same type of toner capsule to replace the toner. After replacing the toner cartridge, press and hold the + and – keys at the same time for five seconds until the number 66 is displayed on the number keys indicating that the toner cartridge has been reset successfully.
2. If the issue persists, escalate it to R&D personnel.