Rinnai Error Code 520: Gas solenoid valve circuit – flame after valve close (Boiler)

Updated October 13, 2026 · by Aurora Star Tech Inc.

Rinnai error code 520 on a boiler means: Gas solenoid valve circuit – flame after valve close. It is also called Rinnai diagnostic code 520.

Critical severityBoilerAlso Combi BoilerI-Series Plus 150K and smaller · I-Series Plus 175K and higher

Homeowner? What Rinnai code 520 means for you

Stop and call Your boiler is reporting: Gas solenoid valve circuit – flame after valve close. This code is a safety shutdown. Turn the boiler off and call a licensed technician. Do not keep resetting it. If you smell gas, leave the house and call your gas utility or 911 from outside.

Safe things you can check yourself

Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
Make sure the unit has power: its on/off switch (often looks like a light switch near the unit) is ON and the breaker in the electrical panel is not tripped.

Call (647) 657-2977 Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does Rinnai error code 520 mean?

The flame rod still senses flame after the board has commanded the gas valve to close.

Applies to: I-Series Plus boilers — 150K BTU and smaller and 175K BTU and higher (Combi and Solo)

Common causes of Rinnai code 520

Loose or damaged gas solenoid valve wiring
Gas solenoid out of resistance/voltage spec
Wet flame rod from a leaking heat exchanger

A technician checks these and 2 other possible causes on site before replacing any part.

Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.

Rinnai models that use code 520

IP060S IP090S IP120S IP150S IP175S IP199S

Other Rinnai Boiler codes

Code	Meaning
371	Indirect tank thermistor fault
380	Exhaust thermistor fault
393	Outdoor temperature sensor fault
400	Water pressure sensor communication fault
430	High or low system water pressure
443	Low water cut-off (LWCO) activated
540	High exhaust (flue gas) temperature
610	Combustion fan motor speed fault
700	PC Board fault
710	Gas solenoid circuit – valve position mismatch
720	Flame rod fault
763	0-10V external control input over-voltage

All Rinnai Boiler error codes →

Rinnai code 520: homeowner questions

What does Rinnai code 520 mean?

Gas solenoid valve circuit – flame after valve close. The flame rod still senses flame after the board has commanded the gas valve to close.

Is it safe to keep using my boiler with code 520?

No. Code 520 is a safety shutdown, so keep the boiler off until a licensed technician has checked it.

Can I reset Rinnai code 520 myself?

Do not keep resetting it. Repeated resets can hide a safety problem; a licensed technician needs to find the cause.

Who can fix Rinnai code 520 near me?

Aurora Star Tech Inc. repairs Rinnai boilers in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.

Homeowner help: Boiler Not Heating: What to Check

Troubleshooting guides

No heat or some zones cold All brands · Boiler

Source: Rinnai Troubleshooting I-Series Plus Boiler Diagnostic Codes (800000375), p.30. Written in our own words as a summary; always check the original manual.

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.