Rinnai is a well-reputed brand that builds super-efficient and low-sustenance tankless water heaters with a lifetime warranty of up to 20 years. These best-selling water heaters, still, may develop problems while in use. These problems can originate from low maintenance and poor installation, component wear and tear, or improper use. Some fixes are very easy and you can DIY at home, while some will need an expert plumber’s assistance.

Are you having issues with a Rinnai tankless water heater? Do you see an error code on the unit’s display or on remote control, and you want help to understand it for proper troubleshooting? Let’s have a look at what steps you can take for Rinnai gas heater troubleshooting.

Just like other manufacturers, Rinnai needs regular cleaning, professional installation, and proper maintenance for excellent performance, water heating, and prolonged unit life.

Here in this article, you will see the most common problems and error codes found in almost all Rinnai water heaters, condensing and non-condensing. Don’t forget that for a valid warranty the Rinnai water heater must only be installed by a licensed Rinnai technician. Extensive skills and knowledge are needed for any electric, plumbing, gas, and tankless work. You can hire a licensed technician from Heating Experts.

Rinnai water heater error codes with meanings and fixes

These heaters have a self-diagnostic system to supervise the working of the unit. When an error occurs, the display unit shows an error code. These error codes vary depending on the  model and brand. We have made an error code guide for you containing the error codes, their meaning, and fix for Rinnai Gas heater troubleshooting.

Error Code




Not working during freeze mode protection

Hire a professional plumber


Power break during a bath fill: water does not heat up when the power returns

A factory reset for the water heater can fix the error


Bypass servo fault including the bypass valves

Turn off the power supply of the water heater. Switch it on. switch on any hot water faucet to heat the unit. If the error stays, replace the bypass valve. 

Circulation flow is under 2.1 GPM 

Make sure the water heater is receiving power.

Make sure the water supply is 30 psi.

See the pump wiring, find out any damaged, loose or broken connections, and put them back if mandatory.

Drain the water tank and see the water inlet filter for any clogginess. If it is blocked, clean or replace it. 

Descale and flush heat exchanger.


Air supply or exhaust blockage

Confirm that the venting material is suitable and Rinnai approved. If not, replace them with Rinnai approved parts. See any blockage or loose connection in the venting system. Make sure that the diameter and vent length is within the right limits and clearance. The most common reason is the poor installation of the vent pipes.


The heater is not turning on

Check that you have the correct gas type and pressure. Ensure there is no air in the gaslight blocking the gas flow. Drain the gas line after turning off the water heater. 

Make sure the ignitor is not clogged and generates no flares. Check the wiring connection. Make sure the burners are seated in a correct manner and there is no dirt and debris.

Final verdict

There are around 30 error codes with different meanings and fixes. For more codes and details you can visit their official website. We tried our best to give you an understanding of the basic error codes with their meanings that you may see while using the Rinnai tankless water heater. Regular maintenance, like cleaning and flushing, will decrease the chances of breakdowns and other issues. Make sure you also reach out to the Rinnai heater technician at Heating Experts to help with heater installation, repair, and services. Call us now at 1300 100 040