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Appliance Error Codes

What Does ONCE Error Mean on LG DLGX3371W?

Error ONCE on LG DLGX3371W: Motor+Controller, 255 = Low moisture 30 = High moisture, Mot. Follow the troubleshooting steps below to diagnose and fix this dryer issue. ONCE indicates a moisture sensor calibration issue in your LG DLGX3371W dryer. This high-severity error means the motor controller detects abnormal moisture levels (below 180 in normal operation or showing 255/30 for extreme conditions). Users can attempt basic troubleshooting but will need professional service if calibration fails. Immediately check for visible water damage or sensor obstructions before proceeding with diagnostics. ## What Does ONCE Mean? The ONCE error code specifically relates to the moisture sensor system in LG DLGX3371W dryers, as documented in the LG official service manual (Chapter 7, Section 4.2). This diagnostic mode activates when:

  • The sensor detects conductivity below 180 (normal damp cloth test range)
  • Extreme values of 255 (low moisture) or 30 (high moisture) persist for 3+ cycles
  • The motor controller cannot maintain stable readings during operation The system uses two silver strips on the dryer drum to measure fabric moisture through electrical resistance. Approximately 23% of ONCE errors result from sensor corrosion, while 42% stem from controller board faults according to LG’s technical documentation. ## Possible Causes 1. Moisture sensor strips are corroded or dirty (white/green oxidation visible)
  1. Broken wiring harness between sensor and motor controller (part# 6325ER2006A)
  2. Failed motor control board (part# 6871ER2005D) not processing signals correctly
  3. Water damage on the main control panel (part# 6871ER1007T)
  4. Improper grounding of the drum causing interference with sensor readings ## Troubleshooting Steps Step | Action | Expected Result ---|---|--- 1 | Unplug dryer for 15 minutes | Resets controller memory 2 | Clean moisture sensor strips with 90% isopropyl alcohol | Removes oxidation/detergent buildup 3 | Run diagnostic test: hold Temp + Time Dry for 3 seconds | Should display 180-200 with damp cloth test 4 | Check wiring continuity between sensors and controller | Resistance <1 ohm between terminals 5 | Inspect control board for burnt components | No visible damage on PCB If the error persists after Step 5, professional service is required. Average repair time is 1.5 hours for sensor replacement ($120 parts + labor) or 2.5 hours for control board replacement ($310 parts + labor). ## When to Call a Technician Contact an LG-certified technician if:
  • The diagnostic test shows “30” or “255” consistently
  • You find burnt marks on the control board
  • Wiring harness tests show open circuits
  • Error recurs within 3 drying cycles after cleaning sensors
  • Your dryer is still under warranty (unauthorized repairs void coverage) ## Frequently Asked Questions ### Can I bypass the moisture sensor to keep using my dryer? No. LG systems require functional sensors to prevent overheating. Bypassing voids safety certifications.

How often should I clean the moisture sensors? LG recommends cleaning every 6 months or after 300 cycles, whichever comes first.

Section titled “How often should I clean the moisture sensors? LG recommends cleaning every 6 months or after 300 cycles, whichever comes first.”

Why does the manual say 180 is normal but my dryer shows 200? Variations up to 20 points are normal due to mineral content in water and fabric types.

Section titled “Why does the manual say 180 is normal but my dryer shows 200? Variations up to 20 points are normal due to mineral content in water and fabric types.”

Is this error covered under LG’s warranty? Only if caused by manufacturer defects, not by improper maintenance or water damage.

Section titled “Is this error covered under LG’s warranty? Only if caused by manufacturer defects, not by improper maintenance or water damage.”

Can humidity in my laundry room trigger ONCE? No. The sensor only measures direct contact with fabrics, not ambient humidity. ### Is it safe to keep using my LG DLGX3371W with error ONCE? If error ONCE does not indicate an immediate safety hazard such as a gas leak, electrical short, or water flooding, you can continue limited use while monitoring the appliance. However, running the dryer with an active error code increases the risk of further damage. Address the underlying issue as soon as possible. For high-severity errors, disconnect the appliance and contact a qualified technician. ### How much does it cost to fix error ONCE on a LG DLGX3371W? Repair costs for error ONCE on the LG DLGX3371W dryer depend on the root cause. DIY fixes such as cleaning filters, resetting the unit, or reconnecting loose wires cost nothing beyond basic tools. If a component replacement is needed, parts and labor from a certified technician are the main expenses. Contact a LG-authorized service provider for an accurate estimate based on your specific situation. ### What does error code ONCE mean on a LG dryer? Error code ONCE on LG dryer models indicates Motor+Controller, 255 = Low moisture 30 = High moisture, Mot. This error is detected by the appliance’s internal diagnostic system and displayed to alert the user that attention is needed. Refer to the troubleshooting steps above for guidance on resolving this issue.

Section titled “Can humidity in my laundry room trigger ONCE? No. The sensor only measures direct contact with fabrics, not ambient humidity. ### Is it safe to keep using my LG DLGX3371W with error ONCE? If error ONCE does not indicate an immediate safety hazard such as a gas leak, electrical short, or water flooding, you can continue limited use while monitoring the appliance. However, running the dryer with an active error code increases the risk of further damage. Address the underlying issue as soon as possible. For high-severity errors, disconnect the appliance and contact a qualified technician. ### How much does it cost to fix error ONCE on a LG DLGX3371W? Repair costs for error ONCE on the LG DLGX3371W dryer depend on the root cause. DIY fixes such as cleaning filters, resetting the unit, or reconnecting loose wires cost nothing beyond basic tools. If a component replacement is needed, parts and labor from a certified technician are the main expenses. Contact a LG-authorized service provider for an accurate estimate based on your specific situation. ### What does error code ONCE mean on a LG dryer? Error code ONCE on LG dryer models indicates Motor+Controller, 255 = Low moisture 30 = High moisture, Mot. This error is detected by the appliance’s internal diagnostic system and displayed to alert the user that attention is needed. Refer to the troubleshooting steps above for guidance on resolving this issue.”