What It Means
No flame proved during the trial-for-ignition period.
Rheem Furnace
Rheem Furnace Error Code 11
Troubleshooting guide for the Rheem Furnace system fault 11.
Possible Causes
- Closed gas valve or empty supply tank.
- Dirty, cracked, or misaligned flame sensor.
- Fouled or weak igniter.
- Corroded wiring or bad ground.
- Failed gas valve or control board.
Not sure which one it is — or if it's none of these? Try ACLogics today.
Disclaimer: This information is for general reference. Error codes can vary by model and production year. Always refer to your machine's specific manual and the information printed on the unit itself.
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Full Diagnosis
No flame was detected by the end of the trial-for-ignition period on a single ignition attempt — the control energized the igniter and gas valve but never proved flame current at all. Rheem/Ruud controls typically retry this sequence a set number of times per call for heat before declaring a full lockout; repeated 11 faults across attempts escalate to the code 10 one-hour soft lockout. This differs from 12, where flame is proved but too weak to hold, and from 14, where flame is sensed when none should exist — 11 is strictly a total no-ignition event.
All Recorded Causes
Gas supply shut off, closed manual valve, or empty LP tank; air in a new gas line; dirty, cracked, or badly positioned flame sensor rod; weak or fouled hot-surface igniter/spark igniter not reaching ignition temperature; poor burner-to-pilot carryover or misaligned burners; loose or corroded ignition/ground wiring; or a failed gas valve or control board not opening the valve on call. Check gas supply and igniter glow/spark first, then sensor condition.
Verify Before Replacing Parts
- Confirm the exact Rheem model family and furnaces context before acting on a generic code description.
- Walk the entire heating sequence in order instead of jumping straight to the reported code, watching for gas supply shut off, closed manual valve, or empty LP tank; air in a new gas line; dirty,….
- Verify each safety device and prove where the sequence stops under live operation, including whether check gas supply and igniter glow/spark first, then sensor condition.
- After the correction, run the system long enough to confirm the furnaces fault does not return under normal load.
Still unsure about this fault?
ACLogics walks you through Rheem Furnace diagnostics step-by-step — so you confirm the cause before swapping parts.
