Description
What it is
The flame sensor (flame rod) that proves the burner has actually lit. It sits in the flame and conducts a small DC microamp current back to the control board; if the board does not see that current it closes the gas valve within seconds as a safety measure. The rod itself is not a wear part in the mechanical sense — it simply oxidises, and cleaning or replacing it is the first thing to try on a short-cycling furnace.
Symptoms it fixes
Furnace lights and then shuts off after 2–10 seconds, repeating the start sequence. Burners never light because the gas valve never opens. The control board locks out after three failed ignition attempts. On Carrier, Bryant, Payne and Day & Night boards these show up as a flame-sensor or open-flame fault code.
Specification
Single-rod sensor with a 73° bend, 1-1/2 in alumina ceramic insulator section, 1/4 in male quick-connect terminal, and a 4-3/4 in wiring harness. Flame rod is high-temperature Kanthal rated to 1800°F. Designed for hot-surface ignition systems and works in both spark-to-pilot and direct-spark ignition systems.
Why a 5-pack
Flame sensors are a routine furnace service item — a professional HVAC tech keeps a handful in the van, a property manager keeps them in every utility closet, and a homeowner with a multi-zone system wants a spare so a winter lockout is a same-day fix rather than a parts wait.
Fits
Carrier, Bryant, Payne and Day & Night gas furnaces using hot-surface ignition, including the 330AAV, 330JAV, 333BAV, 333JAV, 398AAV, 58DHC, 58DXC, 58PAV, 58SSC, 58SXC, 58TUA and 58WAV model families. Also used with the Carrier LH33ZS004 igniter assembly.
Replaces
LH680534 — also cross-references LH680014, LH680012, LH33WZ511, LH33WZ515 and LH33WZ517. Aftermarket equivalents include Supco FLS014.
Fitting
Shut off the gas supply and the electrical power. Remove the single mounting screw, withdraw the rod from the burner and disconnect the wire. Before fitting the new sensor, try cleaning the old rod with fine steel wool or emery cloth — if the furnace then runs normally, keep the new one as a spare. Otherwise fit the new rod, refit the screw and reconnect the terminal, then run a heat cycle and check for a steady flame with no short-cycling.
Before you order
Send us the model number from the furnace rating plate and we will confirm the fit before you buy. If it does not fit, we replace it.
Trademark notice
Carrier, Bryant, Payne, Day & Night and the part numbers listed are trademarks of their respective owners. This listing is not affiliated with, endorsed by, or sponsored by any of them. Part numbers are given only to identify the part this product replaces.
