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Rinnai code 15: Venturi control failure

Continuous flow hot water system (Australia), tankless water heater (United States)

The venturi control in the gas valve assembly is not operating correctly.

This needs a licensed gas technician. There are a few safe checks you can do first, marked below. Anything inside the unit is a job for a professional.

This involves the gas supply or burner. Only a licensed technician should open the unit or work on gas parts.

Only some models show this code. Check the list below.

What causes it

Australian models

  1. The venturi motor or gas valve assembly has failed, or is not receiving voltage when the heater tries to fire.

    Book a licensed gas technician

  2. The combustion fan motor is not running.

    Book a licensed gas technician

US models

  1. Loose or damaged gas valve or solenoid wiring, or a failed gas valve assembly.

    Reset the unit by cycling the powerYou can do this

    1. Switch the unit off at its isolating switch or power point.
    2. Wait at least one minute, then switch it back on and let it try to restart.
    3. If the same code comes back, stop resetting it. Write down the code, model number and serial number before calling for service.
      Repeated resets can mask a fault that needs a technician.

    Book a licensed gas technician

  2. The fan motor is not working, or air flow through the intake and exhaust is restricted.

    Book a licensed gas technician

How to read this code on your unit

Booking a licensed gas technician

Book a licensed gas technicianlicensed gas technician

  1. Turn the unit off and leave the covers on. Gas components must only be serviced by a licensed technician.
  2. Note the code, how often it appears, and the model and serial numbers from the rating label.
  3. Book a licensed gas technician and give them those details.

Models that show this code

41 models in 8 ranges
RangeModels
Heavy Duty (commercial)REU-AM3237WC (HD32e), REU-VCM2837FFC (HD28i), REU-VCM2837WC (HD28e), REU-NB3237WC-AK (Heavy Duty 32C), REU-NB3237FFC-AK, REU-NB3237WC-50-AK, REU-NB3237FFC-50-AK
InfinityREU-AM3237W (Infinity 32), REU-AM2626WDL (Infinity 26 Touch), REU-AM2626WD (Infinity 26), REU-AM2024WD (Infinity 20), REU-AM1620WD (Infinity 16), REU-AM1220WD (Infinity 12), REU-A2626WB (B26), REU-A2024WB (B20), REU-A1620WB (B16)
Infinity BREU-BM2626W (Infinity B26), REU-BM2024W (Infinity B20), REU-BM1620W (Infinity B16), REU-BM1220W (Infinity B12)
Infinity EnviroREU-E2626W (Infinity Enviro 26), REU-E1620W (Infinity Enviro 16), REU-NB3237W-AK (Infinity Enviro 32), REU-NB3237W-50-AK
Infinity internalREU-VCM2837FF (Infinity 28i)
SENSEI commercialCU199i (REU-N3237FFC-US), CU160i (REU-N2530FFC-US), CU199e (REU-N3237WC-US), CU160e (REU-N2530WC-US)
SENSEI residentialRU199i (REU-N3237FF-US), RU180i (REU-N2934FF-US), RU160i (REU-N2530FF-US), RU130i (REU-N2024FF-US), RU199e (REU-N3237W-US), RU180e (REU-N2934W-US), RU160e (REU-N2530W-US), RU130e (REU-N2024W-US)
SENSEI residential with pumpRUR199i (REU-NP3237FF-US), RUR160i (REU-NP2530FF-US), RUR199e (REU-NP3237W-US), RUR160e (REU-NP2530W-US)

Where this comes from

Checked against the manufacturer's manual on 9 October 2026.

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Other Rinnai tankless water heater codes

Code Meaning What you can do
10 Air intake, flue or condensate blockage Safe checks first, then a pro
11 No ignition Safe checks first, then a pro
12 Flame failure or low gas flow Safe checks first, then a pro
13 Combustion fault Safe checks first, then a pro
14 Overheat safety device tripped Call a pro
16 Over-temperature shutdown Safe checks first, then a pro
17 Venturi blockage Safe checks first, then a pro
18 Gas valve adjustment limit Call a pro
19 Electrical earth fault Call a pro
22 Gas valve adjustment fault Call a pro
52 Gas modulating valve fault Call a pro
71 Gas solenoid valve failure Call a pro

See all gas valve fault codes on tankless water heaters across brands.