How To Fix Water Heater Temperature Sensor Failure

To fix a temperature sensor failure in a water heater, first check the wiring, then replace the faulty sensor or thermostat as needed for accurate temperature readings.

A failing temperature sensor can leave you without hot water. Learn how to diagnose and fix this common water heater problem with our step-by-step guide.

Fixing a faulty water heater temperature sensor

Signs of a Faulty Temperature Sensor

Watch for these warning signs:

  • Inaccurate temperature readings on display
  • Error codes like “Sensor Failure”
  • Water too hot or not heating at all
  • Heater cycling on/off frequently
Diagnosing temperature sensor failure water heater

Diagnosing the Problem

Basic Checks First

Before replacing parts:

  1. Power cycle the unit
  2. Check wiring connections
  3. Clean sensor contacts

Testing the Sensor

Use a multimeter to check resistance. Compare readings to manufacturer specs. Most sensors should show 10-50k ohms at room temperature.

Replacement Process

For Raypak Models

As mentioned in this Raypak case:

  1. Turn off power and water supply
  2. Remove front and side panels
  3. Disconnect pressure switch wire
  4. Unscrew sensor retaining nut
  5. Install new sensor (PN 009577F for many models)

For Rheem Water Heaters

Similar process but may require accessing the igniter area first.

Preventing Future Issues

Prevention Method Benefit
Annual maintenance Catches early corrosion
Water treatment Reduces mineral buildup
Proper installation Prevents vibration damage

When to Call a Professional

Consider professional help if:

  • Error persists after replacement
  • You suspect control board issues
  • Gas lines need disconnection

For complex systems like tankless water heaters, professional service may be safer.

Cost Considerations

Typical sensor costs $20-$80. DIY installation saves $150-$300 in labor. Always use OEM parts when possible for proper calibration.

Additional Resources

The U.S. Department of Energy offers water heater maintenance tips. For sensor specifications, consult your manufacturer’s manual.

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Joye
Joye

I am a mechanical engineer and love doing research on different home and outdoor heating options. When I am not working, I love spending time with my family and friends. I also enjoy blogging about my findings and helping others to find the best heating options for their needs.