Rheem 11 Error Code: Gas shut-off valve not fully open
Updated October 2026 · Sourced from Rheem documentation
🧭 Check a few things first
The manual lists this code as the gas shut-off valve not being fully opened.
Is it safe to keep running? Check the steps below first. If the valve is fully open and the code returns, turn the heater off and call a qualified service technician. Never work on gas piping yourself.
11 at a glance
| Code / how it shows | Meaning | Applies to |
|---|---|---|
| 11 Shown on the LED display of the remote control | Gas shut-off valve not fully open | 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.
- Look at the gas shut-off valve to the water heater and make sure it is fully open (handle in line with the pipe), as the manual says.
- If you smell gas at any time, do not touch switches, leave the building and call your gas supplier from outside.
- After opening the valve, run a hot water faucet and see if the code clears.
🛑 Stop and call a licensed pro if
- If the valve is fully open and the code returns, turn the heater off and call a qualified service technician. Never work on gas piping yourself.
- 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.
Ryan Giles · Red Seal Certified Plumber · Ask a plumber · Ask an HVAC technician
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