T012_F Low Flame Sense
Status
The status of this fault is non-critical and furnace operation will continue as normal in heating (and all other) mode(s). If flame sense is low, the furnace control (or I.F.C.) may soon no longer be able to properly sense the flame and status of the problem may be elevated to the level of fault code "13" or fault "11" (if flame can not be sensed at all).
Description
The flame sense current from the flame sense rod at the furnace control (or I.F.C.) is weak or marginal at best.
Expected Operation
All operation (including gas heat) will proceed as normal with only the fault code ("12") displayed at the furnace control (I.F.C.) and "LO FLAME SENSE" displayed in the fault area of a communicating thermostat.
Cause
1. The most common cause for low flame sense during heat operation is that the flame sense rod may need cleaning or may not be properly connected or wiring between the rod and the furnace control may be shorted or opened.
2. Another cause for low flame may be an improperly mounted or poorly grounded flame sensor.
Solution
1. Clean or replace the flame sense rod or check all connections and wire between the rod and the furnace control (or I.F.C.).
2. Reinstall or replace flame sensor and check wiring and connections. Also make sure the furnace is properly grounded.
