Rinnai Water Heater Code 11: What It Means and How to Fix It

Last updated: October 5, 2026 · Codes covered: 11 · Sources

Verify in your manual: Code 11 checks vary by Rinnai series (SENSEI, condensing, non-condensing, indoor, outdoor); confirm in your model's Installation and Operation Manual.

Code 11 on a Rinnai tankless water heater means "no ignition": the heater tried to light its burner and couldn't, so it shut down. The most common causes are simple, like a closed gas valve or an empty propane tank, and you can check those safely yourself. Anything involving the gas line, burner, or internal parts is a job for a licensed technician.

What the 11 code means

Rinnai's manuals call code 11 "No Ignition" (the current SENSEI N-Series manual adds "Heater Not Turning On"). Rinnai tankless heaters have no pilot light. When you open a hot tap, an electronic igniter lights the burner. If it can't light, the heater stops and shows 11 on the controller.

You'll usually notice that the water at your taps stays cold.

Look-alike codes that mean something different:

• Code 12 is a flame failure ("No Flame" in newer manuals). Many of the same checks apply.
• Code 10 points to an air supply or exhaust blockage (or a full condensate trap on condensing models).

Rinnai's published code tables use the same name for code 11 across its tankless series, but the detailed checks vary by model. Keep your model's Installation and Operation Manual handy.

Likely causes (most common first)

1. Gas turned off at the water heater. The manual gas valve below the heater is closed or only partly open. This often happens after other work in the house.
2. Empty or low propane tank. On propane (LP) systems, Rinnai's first checks include making sure there's gas in the tank.
3. Gas off at the meter or interrupted by the utility.
4. Air in the gas line, typically after a new install or gas work. Bleeding the line is an installer's job.
5. Wrong gas type or wrong gas pressure. The heater has to match your gas (natural gas vs. propane), and the supply pressure has to be in range. An undersized gas line can also cause this. Only a licensed pro can check these.
6. Blocked condensate line (condensing models). Rinnai lists a blocked condensate line among the code 11 checks.
7. Igniter, flame rod, gas valve, or control board problem. Rinnai's checklist includes the igniter, flame rod wiring, gas solenoid valves, the gas orifice, and the control board ground wire. All of these are internal parts and need a technician.

How to fix it, step by step

Do these in order and try a hot tap after each step. Stop at any point if you smell gas.

1. Reset the heater.
   • Turn off all hot water taps.
   • Press the On/Off button on the temperature controller to switch the heater off, wait a few seconds, then switch it back on.
   • Open a hot tap again. Rinnai notes that codes 11 and 12 reset once water flow stops for a few seconds and then starts again. (That note comes from a bulletin for multi-unit systems, so check your manual for your model's exact reset.)
2. Check the manual gas valve at the heater. It's usually right below the unit. Rinnai says to turn it by hand only, never with tools. If the handle is crosswise to the pipe, it's probably closed.
   • If it won't turn by hand, don't force it or try to repair it. Call a qualified technician.
   • If you find it closed, follow the "Operating Instructions" label on your heater (also in your manual) to turn the gas back on. That includes waiting 5 minutes and smelling for gas before you turn it on.
3. Make sure other gas appliances work. Try the stove burner, gas dryer, or furnace. If none of them work either, the problem is your gas supply, not the water heater. Call your gas utility (natural gas) or your propane supplier.
4. Check the propane tank gauge (LP systems). If it's low or empty, call your propane supplier. Let them refill it and get the gas back on. Don't reconnect or relight anything on the supply side yourself.
5. Think about recent gas work. After a new install or a gas shutoff, air in the line is a likely cause. Call your installer or a licensed gas technician. Don't loosen fittings to "bleed" the line.
6. Check the outside vent and condensate drain. Clear snow, leaves, or nests from the vent termination (or from the heater itself on outdoor models) without taking anything apart. On condensing models, make sure the condensate line isn't kinked, frozen, or clogged at the end.
7. Check the power. Make sure the heater is plugged in and its breaker is on. It needs power to light.
8. Stop and call a pro if 11 keeps coming back. Everything past this point (gas pressure, gas type, igniter, flame rod, gas valve, control board) involves live gas or live voltage. Leave it to a licensed technician.

Test the part

The parts behind code 11 (igniter, flame rod, gas valve) sit right at the burner and gas controls. Testing them isn't a homeowner job. Here's what you can safely check.

1. Unplug the water heater and turn off the gas. Pull the power cord or switch off its breaker. Rinnai notes that the temperature controller doesn't cut the power. Then turn the manual gas valve below the heater to OFF, by hand only.
2. Look over the power cord and plug. Check for damage, scorch marks, or a loose plug. Rinnai says not to use an extension cord or adapter.
3. Look at the gas connector from the outside only. Check for obvious damage, like a crushed or kinked flexible line. Don't touch, tighten, or loosen any fitting. If anything looks damaged, or you smell gas, leave and call your gas company.
4. Check the vent and condensate drain outside the cabinet. The vent end should be clear and the condensate line should be draining and open at its end.
5. Look for water damage. Rust streaks or water stains under the unit are a warning sign. Rinnai says not to use the heater if any part has been under water.
6. Don't take off the front panel to test parts. Rinnai says the front panel should only come off for service. Its igniter, flame rod, and gas valve checks include live tests with the heater running. Those are for a licensed technician, so no meter readings are given here.

When you're done, open the gas valve by hand and restore power following the "Operating Instructions" label.

Safety notes

When to call a pro

Call a licensed plumber or gas technician, or Rinnai, if:

• Code 11 keeps coming back after a reset, and the gas is on and other gas appliances work.
• The heater is new, was just converted, or the gas was recently worked on.
• You suspect the gas line is too small or the gas pressure is wrong. Rinnai lists gas type, inlet pressure, and gas line sizing among its code 11 checks.
• You see damage, rust, water, or scorching on or under the heater.
• The heater is under warranty. Rinnai recommends licensed professionals for installation and service, and changes to the appliance can void the warranty.

Rinnai Customer Care is at 1-800-621-9419, Monday to Friday, 8 a.m. to 8 p.m. ET (per Rinnai's FAQ page). Have your model number and the code ready.

FAQ

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