Rheem 12 Error Code: Gas service interrupted or LP gas running low
Updated October 2026 · Sourced from Rheem documentation
The manual lists this code for two causes: gas service has been interrupted, or (LP models only) LP gas is running low.
Is it safe to keep running? Check the steps below first. If gas supply is normal and the code remains, call a qualified service technician. For a suspected gas supply interruption the manual says to contact your gas utility company.
12 at a glance
| Code / how it shows | Meaning | Applies to |
|---|---|---|
| 12 Shown on the LED display of the remote control | Gas service interrupted or LP gas running low | Rheem non-condensing tankless gas water heaters (160,000, 180,000 and 199,900 Btu/h models) with remote control display |
Check this first
Only steps a homeowner can do safely. Do not open electrical panels or the burner area.
- Check whether other gas appliances in the home are working, which can show a gas supply interruption.
- On LP (propane) models, check the level in the LP tank. The manual says to refill or replace the LP gas container.
- If you smell gas, do not touch switches, leave the building and call your gas supplier from outside.
🛑 Stop and call a licensed pro if
- If gas supply is normal and the code remains, call a qualified service technician. For a suspected gas supply interruption the manual says to contact your gas utility company.
- You smell gas. Leave the house, do not touch switches, and call your gas utility from outside.
- Codes for flame failure, overheating, venting or the control board that return after one reset.
- Water leaking from the heater, the relief valve discharging, or scorching around the burner area.
- A carbon monoxide alarm sounds. Get everyone outside and call 911 or the fire department.
Safe first steps for any Rheem code
- Write down the exact code shown on the controller or the number of status light flashes.
- Turn the water heater power off and back on (or press the reset button the manual describes) once. If the code comes back, stop resetting.
- Make sure the gas supply valve to the heater is open and other gas appliances in the home are working.
- Make sure the cold water supply valve is fully open and hot water taps are not partly closed.
- Look at the outside vent terminal for snow, ice, leaves or anything blocking it (look only).
Source: Rheem High-Efficiency Non-Condensing Tankless Water Heater Use and Care Manual, Service Error Code Chart, p. 77. Codes are series-specific, so your unit's own manual is the final word. Reviewed October 2026.
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