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E521LG Washer

LG Washer Error E521 – Meaning, Causes & How to Fix

The appliance control system detected a condition indicating temperature sensor fault – thermistor readings are outside expected range.

Medium Severity
Low
Medium
High
Critical

Expert Verified

Reviewed by a Certified Electrical Engineer & Licensed Technician

Official Meaning

The appliance control system detected a condition indicating temperature sensor fault – thermistor readings are outside expected range.

Real-World Causes

  • 1Faulty inlet valve solenoid
  • 2Blocked drain hose or pump filter
  • 3Kinked or bent inlet hoses restricting water flow
  • 4Sensor damaged by moisture or mineral buildup
  • 5Clogged inlet filter screens

Symptoms

Look for these signs to confirm error E521 on your LG Washer:

  • Very slow filling or draining behavior
  • Appliance stops mid-cycle
  • Machine pauses and displays the error
  • Error displayed at the start of a cycle

DIY Fix (Safe)

  1. 1Verify household water and power supply conditions
  2. 2Inspect hoses and filters for blockages
  3. 3Restart appliance after disconnecting power for 5 minutes
  4. 4Clean filters and sensors if accessible
  5. 5Run diagnostic mode if available

Professional Action Required

  1. 1Test valves, sensors, and motors with a multimeter
  2. 2Inspect wiring harness and connectors
  3. 3Replace defective pumps, motors, sensors, or valves
  4. 4Inspect control board relays
  5. 5Replace electronic control board if failure is confirmed

Additional Context

Load Type
Any load type
Drain Related
Depends on cycle stage
Sensor Issues
Sensors may give incorrect readings if hoses are blocked

Frequently Asked Questions

What does LG Washer error E521 mean?
The appliance control system detected a condition indicating temperature sensor fault – thermistor readings are outside expected range.
What causes LG Washer E521 error?
Common causes include: Faulty inlet valve solenoid, Blocked drain hose or pump filter, Kinked or bent inlet hoses restricting water flow.
How do you fix LG Washer error E521?
Start with these DIY steps: Verify household water and power supply conditions. Inspect hoses and filters for blockages. If the error persists, professional service may be needed.

Related Error Codes

Other LG Washer Errors

E215The appliance control system detected a condition indicating motor control error – the controller cannot communicate with drive motor
E209The appliance control system detected a condition indicating drain system failure – water cannot remove water properly
E1The appliance control system detected a condition indicating communication error – internal control boards lost connection
E564The appliance control system detected a condition indicating drain system failure – water cannot remove water properly
E246The appliance control system detected a condition indicating temperature sensor fault – thermistor readings are outside expected range
E765The appliance control system detected a condition indicating temperature sensor fault – thermistor readings are outside expected range
E319The appliance control system detected a condition indicating temperature sensor fault – thermistor readings are outside expected range
E314The appliance control system detected a condition indicating temperature sensor fault – thermistor readings are outside expected range

About the Author

Technical Review Team

Reviewed by certified technicians with 10+ years of LG repair experience. Every error code is verified against manufacturer service manuals and real-world repair data.