Error Code 11 on Your Rinnai Tankless Water Heater? Here are 5 Areas to Check

Do you have a Rinnai tankless water heater that is giving you an error code 11? This error code can be incredibly frustrating – not only because it means the ignition is off and you aren’t getting hot water, but also because there are several potential causes. Have no fear because we’re here to help you decode the error so you can troubleshoot and fix the problem.

An error code 11 on a Rinnai tankless water heater can appear due to an issue with the ignitor, gas supply, flame rod, venting, excess moisture, and more. Finding the exact cause is important to apply the right solution and get your water heater running again. 

Let’s dive deeper into each issue and see what you can do to test and possibly fix the problem.


  • Cycle the unit and check that there is a spark from the ignitor. If there is no spark, it could mean there could be loose or damage components, or that the voltage of the electric board is incorrect
  • Check for build-up on the ignitor. If you notice scale or carbon, follow the manufacturer’s instructions for cleaning and removing build-up. 

Gas supply

  • Is the gas supply on to your home? Check other gas-powered appliances such as your stove, laundry drier, etc. 
  • It’s possible that the gas pressure is incorrect, which can happen if dirt or debris gets caught in the system.
  • If the Rinnai water heater was recently installed, air may need to be purged from the gas lines.

Flame rod

  • Inspect the flame rod and make sure that the wiring look is in good condition and all connections appear secure.
  • Look for any dirt or debris on the flame rod or gasket, and clean if needed. If the parts appear damaged or cracked, they will need to be replaced.


  • Clean out any blockages in the intake and exhaust vents.
  • Faulty venting components or installation can impact airflow and lead to build-up on flame rods.

Water and moisture

  • Look for signs of leaks or excessive moisture on the unit, which could corrode parts or impact electrical connections.
  • For condensing units, inspect the condensate drainage.

Tankless water heater repair in New Haven and Fairfield County

If you’re dealing with an error code with your Rinnai tankless water heater, don’t get frustrated – get professional help! At Rick’s Plumbing, our experienced plumbers can troubleshoot your water heater and provide quality repair service. To schedule an appointment, call us at (203) 874-6629 today.