Rinnai Tankless Water Heater Error Code 10: Meaning & How to Fix It

By the ErrorCodePro Editorial Team · Last reviewed October 20, 2026

Rinnai tankless water heater error code 10 means: There's an air supply or exhaust blockage, or the condensate trap is full (the trap applies to SENSEI models only). [1] Keep using it? No hot water until it's resolved. Don't keep resetting it.. Start with the owner checks below, beginning with: check the condensate drain.

Smell gas? Leave the building now. Do not touch light switches, phones or appliances inside. Call your gas utility or 911 from outside. CO alarm sounding or headache, dizziness or nausea? Get everyone outside and call 911. Gas valves, burners, venting and wiring are for a licensed technician only. See our safety policy.

Quick facts

Code	10
Also shown as	None listed by the manufacturer
Brand / appliance	Rinnai tankless water heater (sensei and non-sensei tankless water heaters)
System	Venting / airflow
Official meaning	There's an air supply or exhaust blockage, or the condensate trap is full (the trap applies to SENSEI models only). [1]
Keep using it?	No hot water until it's resolved. Don't keep resetting it.
DIY-safe?	Owner checks only (listed below)
Support	Rinnai support, 1-800-621-9419

On this page: Meaning · Steps · Parts · When to call a technician · Related codes · FAQ

What error code 10 means on a Rinnai tankless water heater

There's an air supply or exhaust blockage, or the condensate trap is full (the trap applies to SENSEI models only). [1]

This is a venting / airflow code. Codes and wording can vary by model, so check your owner's manual for your model number.

How to fix Rinnai tankless water heater error code 10 (safe owner checks)

Owner checks only: on heating, cooling and water-heating equipment, limit yourself to reading the code and checking the thermostat, breaker and service switch, air filter, condensate drain, that the gas supply valve is open (no disassembly) and that vent terminals are clear of snow or debris. Reset power only if your manual allows it.

Safety first: disconnect power before you remove any panel or reach into the sump or drum. Do not touch wiring, the control board or the motor. If you see water near electrical parts, stop and call a technician. These steps are based on Rinnai's published guidance [1], rewritten for clarity.

Check the condensate drain. On condensing models, make sure the condensate line is draining and isn't clogged or frozen.
Clean the inlet air filter. On SENSEI models, clean the inlet air filter under the front cover (top right).
Check the vent terminals. Outside, make sure the intake and exhaust terminals are free of snow, ice, leaves, nests or other obstructions. Don't disconnect any vent pipe.

Parts that may be involved

Exact parts depend on your model number. This page lists part types only, never part numbers.

No specific part is implied by the manufacturer's guidance for this code.

When to call a technician

Vent inspection and disassembly is a carbon monoxide risk: licensed technician only
Gas pressure, gas valve, igniter, flame rod, venting or combustion problems: licensed plumber or gas technician
Gas valves, burners, igniters, flame sensors, venting/flue or CO concerns: licensed HVAC technician or plumber
Refrigerant work: EPA 608-certified technician only
Smell of gas: leave and call the gas utility or 911
Anything involving wiring, the control board, the motor or the water valve electrics
The appliance is under warranty: contact Rinnai support, 1-800-621-9419 first

Frequently asked questions

What does error code 10 mean on a Rinnai tankless water heater?

Rinnai lists 10 as follows: There's an air supply or exhaust blockage, or the condensate trap is full (the trap applies to SENSEI models only).

Is it safe to keep using the tankless water heater with 10?

No hot water until it's resolved. Don't keep resetting it..

Can I fix Rinnai tankless water heater error 10 myself?

Only with the owner checks on this page, starting with: check the condensate drain. If it persists, call a technician or Rinnai support, 1-800-621-9419.

Sources

https://media.rinnai.us/salsify_asset/s-3e3cd69f-0edc-4b85-8d6d-93b39057fab5/100000652-Troubleshooting%20TWH%20Diagnostic%20Codes.pdf (official)

Last reviewed: October 20, 2026. ErrorCodePro is not affiliated with Rinnai.