Rinnai · Tankless Water Heater Moderate

02 — Power Interruption / Memory Loss

The unit lost power or experienced a brownout and the control board reset. Often appears after a storm or breaker trip.

Keep using it?
Yes, with caution
DIY difficulty
Easy
Verified against
rinnai.us ↗

How to fix it

  1. Turn the unit off at the controller and unplug or kill the breaker for 60 seconds.
  2. Restore power and re-set temperature on the remote.
  3. Verify the breaker is fully seated and the outlet/whip is tight.
  4. Check voltage at the unit — should be ~120V AC stable.
  5. If code returns with no outage, replace the PCB.

Why it happens

Typical signs: Unit not responding to demand · Code 02 on remote/display · Settings reverted to defaults

  • Power interruption Brief outage or voltage sag reset the PCB.
  • Loose power connection Plug, hardwire, or terminal block not making solid contact.
  • Tripped breaker Breaker partially tripped or fluctuating.
  • Failing PCB Control board losing memory on its own indicates board failure.

More Rinnai tankless water heater codes

03 03 — Loss of Communication / EZConnect Issue 10 10 — Air Supply or Exhaust Blockage 11 11 — No Ignition 12 12 — Flame Failure 14 14 — Thermal Fuse / Overheat Cutoff 16 16 — Outgoing Water Over-Temperature

All Rinnai codes → All tankless water heater codes →

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician. Verified against manufacturer documentation: rinnai.us.