Rinnai Tankless Water Heater Error Code 03: How to Fix It
Medium 30-60 minutes Medium Severity
Verified June 2026
- Error Code
- 03
- Brand
- Rinnai
- Product Type
- water_heater
- Severity
- Medium
- DIY Difficulty
- Medium
- Estimated Fix Time
- 30-60 minutes
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Tools You'll Need
- Phillips screwdriver
- Multimeter
- Replacement heating element module
How to Fix Error Code 03
-
Turn Off Power and Gas
Always disconnect power and gas before servicing. -
Check for Loose Connections
-
Reset the Water Heater
-
Test the Heating Element Module
Use a multimeter safely; avoid touching live wires. -
Replace the Heating Element Module
Ensure gas lines are properly sealed to prevent leaks. -
Test the Unit
Parts You May Need
Heating element module
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Heating element module
Check Price on Amazon
Heating element module
Check Price on Amazon
Heating element module
Check Price on Amazon
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When to Call a Professional
If you are not comfortable working with gas lines or electrical components, or if the error persists after replacing the heating element module, contact a licensed plumber or HVAC technician.Frequently Asked Questions
What does error code 03 mean on a Rinnai water heater?
Error code 03 indicates a heating element module fault. This module controls the burner and is essential for operation.
Can I still use my Rinnai water heater with error code 03?
No, the unit will not operate when this error is active. It must be fixed to restore hot water.
How much does it cost to replace a Rinnai heating element module?
The module itself typically costs $50-$150, plus labor if you hire a professional. DIY replacement saves on labor.
Is error code 03 the same as error code 03 on other units?
Error codes vary by manufacturer. On Rinnai, 03 is specifically a heating element module fault.
Can a power outage cause error code 03?
Sometimes a power surge can trigger the error. Try resetting the unit first; if it returns, the module may be damaged.