Hayward Flame Sensor, Low NOx/Universal

The Hayward IDXLFLS1930 is the genuine flame sensor for the Universal H-Series Low NOx heaters, models H150FD through H400FD, and for the earlier H-Series Low NOx 250 and 400.

What it does

Once the ignitor lights the burner, the flame sensor confirms to the control board that a flame is present. Without that signal the board closes the gas valve within seconds. A heater that lights, runs briefly and drops out, then retries, is the classic sign.

Clean before you replace

A coated sensor rod gives the same symptom as a failed one, so it is worth cleaning the rod first. If the fault continues, fit this sensor. The ignitor is a separate part.