390C711

OKI C711 Error 390: Troubleshooting Guide

The OKI C711 error 390 is a thermal fault notification for the toner fixing system. This issue typically occurs when the fuser's internal sensor detects temperature values outside the standard operating range. The most common fix is a full power cycle, allowing the heating element to reset safely. This printer model is built for heavy-duty office use, meaning fuser wear is a common cause after extended duty cycles.

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Common causes

  • 1Thermistor failure causing incorrect heat detection.
  • 2Paper jam obstructing the fuser output area.
  • 3Insufficient power input preventing proper heating.
  • 4Natural wear and tear of the internal fuser gears.

Solutions

Quick Diagnostics

The C711 error 390 is signaled by an immediate motor halt and a specific message on the LCD control panel. If you hear grinding noises before the message appears, it is a clear indicator that the fuser unit is experiencing a mechanical blockage.

Step-by-Step Solution

  1. Power Cycle: Turn off the printer and unplug it for 10 minutes to allow the thermal sensor to reset.
  2. Check Fuser: Open the rear cover and verify there are no paper jams or debris in the fuser unit.
  3. Verify Power: Connect the printer directly to a wall outlet instead of a power strip to ensure stable voltage.
  4. Test Print: Turn the unit back on and run a test page to check if the fuser reaches operational temperature correctly.

Maintenance and Prevention

Avoid using heavy cardstock that might strain the fuser path. Clean the paper feed rollers with compressed air every 6 months. Use genuine toner cartridges to ensure the melting point matches the fuser’s specifications.

When to Call a Technician

If the error code persists after following these steps, the fuser’s halogen lamp or thermistor may have failed entirely, requiring professional hardware replacement.

Technical Data

  • Technology: Digital LED Single Pass
  • Print Speed: Up to 34 ppm color
  • Connectivity: USB 2.0 and Ethernet 10/100
  • Paper Capacity: 630 sheet standard input
  • Compatible Consumables: C711 Series (Original High-Capacity Toner)
  • Recommended Use: Heavy Office Environment
  • Official Drivers / Firmware

Steps to follow

  1. 1

    Power Cycle

    Turn off the printer and unplug it for 10 minutes to allow the thermal sensor to reset.

  2. 2

    Check Fuser

    Open the rear cover and verify there are no paper jams or debris in the fuser unit.

  3. 3

    Verify Power

    Connect the printer directly to a wall outlet instead of a power strip to ensure stable voltage.

Frequently asked questions

This code points to a temperature fault in the fuser unit, usually caused by a sensor failing to detect proper heating levels.

Yes, it is a hardware error that prevents operation. If a power cycle doesn't resolve it, the fuser unit needs professional assessment.

Original consumables are highly recommended to prevent premature wear on the fuser rollers.

A professional maintenance check is recommended every 50,000 pages to avoid excessive toner buildup.