What causes Rinnai Tankless Water Heater 61?

A loose, broken or damaged connection in the wiring harness between the combustion fan motor and the PC board. Debris in the fan housing, or a blower wheel that doesn't turn freely. On SENSEI condensing models, a check valve behind the fan motor sticking in the closed position. A fan motor with open windings, or a motor that has failed even though its windings test in spec. A faulty PC board, which Rinnai lists as the last step after the fan checks.

How do I fix Rinnai Tankless Water Heater 61?

Write down the code and your model number, and note whether the heater is a SENSEI (condensing) model, since one of Rinnai's steps applies only to SENSEI units. If you smell gas at any point, stop, leave the house and call your gas utility from outside. To see whether 61 is a repeat, you can view the code history on models with the standard controller: turn the heater off with On/Off, then press and hold On/Off for 2 seconds and the Up button together. The last nine codes flash one after another; repeat the same press to exit and turn the heater back on. Don't open the unit or unplug the fan yourself. Rinnai's manuals warn that some checks should be done only by a trained and qualified professional, and that plugging or unplugging the motor with power on can damage it. Call a licensed plumber or gas technician, or Rinnai. If the heater is under warranty, talk to Rinnai or an authorized technician before anyone replaces parts.

When should I call a pro for Rinnai Tankless Water Heater 61?

Checking the wiring harness from the fan motor back to the PC board for loose, broken or damaged connections. With power and gas off, removing the fan motor, confirming the blower wheel turns freely and clearing any debris from the fan housing. On SENSEI models, making sure the check valve behind the fan motor isn't stuck closed. Measuring the motor winding resistance against the technical data sheet behind the front cover or the service manual, and replacing the motor if the windings are open. Replacing the fan motor if the windings are in spec and it turns freely, and replacing the PC board only after that, as Rinnai's sequence directs.

Code: 61🚿 Rinnai Tankless Water Heater

Rinnai Tankless Error Code 61: Combustion Fan Failure (Meaning, Causes, Fixes)

Q: What does Rinnai Tankless Water Heater 61 mean?

Code 61 on a Rinnai tankless water heater means a Combustion Fan problem: the fan that pushes air through the burner isn't running the way the control board expects. It applies to both SENSEI condensing and non-SENSEI models. Rinnai's fixes for 61 are all inside the unit (fan wiring, fan wheel, motor windings, then the motor or PC board), so this is a job for a licensed technician. Rinnai's installation manuals list code 61 as Combustion Fan (the VA indoor manual calls it Combustion Fan Failure). The combustion fan supplies the air the burner needs and pushes exhaust out through the vent, so the heater won't fire safely when the board sees a fan fault. Rinnai's Troubleshooting Tankless Water Heater Diagnostic Codes manual says code 61 applies to both SENSEI and non-SENSEI series. Its steps, in order, are: check the wiring harness from the fan motor back to the PC board for loose, broken or damaged connections; with power and gas off, remove the fan motor and make sure the blower wheel turns freely; check the fan housing for debris that could stop the wheel; on SENSEI models only, make sure the check valve behind the fan motor isn't sticking closed; measure the motor winding resistance against the technical data sheet behind the front cover or the service manual and replace the motor if the windings are open; replace the fan motor if the windings are in spec and it turns freely; and finally replace the PC board. Rinnai warns never to plug or unplug the motor while power is on, because that can damage the fan motor and other parts.

Reviewed 2026-10-23 · Based on 5 manufacturer & service sources

What the code means

Rinnai's installation manuals list code 61 as Combustion Fan (the VA indoor manual calls it Combustion Fan Failure). The combustion fan supplies the air the burner needs and pushes exhaust out through the vent, so the heater won't fire safely when the board sees a fan fault. Rinnai's Troubleshooting Tankless Water Heater Diagnostic Codes manual says code 61 applies to both SENSEI and non-SENSEI series. Its steps, in order, are: check the wiring harness from the fan motor back to the PC board for loose, broken or damaged connections; with power and gas off, remove the fan motor and make sure the blower wheel turns freely; check the fan housing for debris that could stop the wheel; on SENSEI models only, make sure the check valve behind the fan motor isn't sticking closed; measure the motor winding resistance against the technical data sheet behind the front cover or the service manual and replace the motor if the windings are open; replace the fan motor if the windings are in spec and it turns freely; and finally replace the PC board. Rinnai warns never to plug or unplug the motor while power is on, because that can damage the fan motor and other parts.

Likely causes

A loose, broken or damaged connection in the wiring harness between the combustion fan motor and the PC board
Debris in the fan housing, or a blower wheel that doesn't turn freely
On SENSEI condensing models, a check valve behind the fan motor sticking in the closed position
A fan motor with open windings, or a motor that has failed even though its windings test in spec
A faulty PC board, which Rinnai lists as the last step after the fan checks

Safe DIY checks

⚠ Before you start

Unplug the appliance (or switch off its breaker) and shut off the water supply valves before removing panels or disconnecting hoses. Keep towels handy for residual water.

Write down the code and your model number, and note whether the heater is a SENSEI (condensing) model, since one of Rinnai's steps applies only to SENSEI units.
If you smell gas at any point, stop, leave the house and call your gas utility from outside.
To see whether 61 is a repeat, you can view the code history on models with the standard controller: turn the heater off with On/Off, then press and hold On/Off for 2 seconds and the Up button together. The last nine codes flash one after another; repeat the same press to exit and turn the heater back on.
Don't open the unit or unplug the fan yourself. Rinnai's manuals warn that some checks should be done only by a trained and qualified professional, and that plugging or unplugging the motor with power on can damage it.
Call a licensed plumber or gas technician, or Rinnai. If the heater is under warranty, talk to Rinnai or an authorized technician before anyone replaces parts.

🛠 When to call a pro

Checking the wiring harness from the fan motor back to the PC board for loose, broken or damaged connections.
With power and gas off, removing the fan motor, confirming the blower wheel turns freely and clearing any debris from the fan housing.
On SENSEI models, making sure the check valve behind the fan motor isn't stuck closed.
Measuring the motor winding resistance against the technical data sheet behind the front cover or the service manual, and replacing the motor if the windings are open.
Replacing the fan motor if the windings are in spec and it turns freely, and replacing the PC board only after that, as Rinnai's sequence directs.

Sources

Last reviewed 2026-10-23. Always confirm against the manual for your exact model number.

Rinnai Tankless Error Code 61: Combustion Fan Failure (Meaning, Causes, Fixes)

What the code means

Likely causes

Safe DIY checks

🛠 When to call a pro

Related codes

Sources