Appliance Diagnostic

Rheem Furnace Code 11 - Ignition Failure / No Flame Detected

Code 11 triggers on Rheem and Ruud furnaces when main flame is not established within 4 seconds of gas valve opening.

What Caused This Error?

The control system reports 11 when the monitored condition described by the error code is outside the expected operating range. In this case, the most likely trigger is gas supply valve shut off or gas line air lock. Other common contributors include dirty or defective hot surface igniter and faulty gas valve solenoid coil.

Step-by-Step Diagnostic Check

  1. Disconnect electrical power before opening panels. Confirm shutoff gas valve handle is parallel to pipe line.
  2. Disconnect electrical power before opening panels. Check igniter for white hot spots or cracks; test resistance (typical 40-90 ohms).
  3. Clean flame sensor probe with steel wool.
  4. Replace hot surface igniter.
Most Likely Replacement Part

Hot Surface Igniter (HSI)

OEM Part #: MODEL-SPECIFIC

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