Furnace thermostat error flashing

Furnace thermostat error flashing can mean various things and a homeowner should know what it means before worrying about callouts.

A furnace flashing a code, “two quick flashes followed by two slower flashes,” is not uncommon but it can be devastating if the home will not heat up.

A furnace has diagnostic sensors known as “set points” that may turn on automatically to detect the problem. The homeowner may just need to reset these set points by turning off power to the furnace and unplugging it for five to fifteen minutes and then plugging back in.

Furnaces with outdoor units can experience intermittent symptoms before failing to cycle properly or consistently (outside code) four quick flash cycles followed by a long flash and short pause. The air handler’s electronic control module inside may not have enough power, or it was disconnected by accident, or there is an error reading input from one of the sensors. A qualified heating service technician should know the furnace codes that come, heater diagn

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A three-way valve is a safety measure that detects when dangerous back pressure is generated, shuts off the gas completely until all pressure is released, and resumes operation.

I’ll link to a demo of the furnace thermostat flashing error. This phenomenon is pretty rare but there are ways to deal with this error to resume normal operation

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There seems to be no problem with the flame yet the furnace keeps showing an error. It flickers like it’s going out

Occasionally, your thermostat will show a flashing E4 or E5 code on its screen. This can happen for three different reasons: 1) If your system’s electronic ignition fails now and then, a good night of sleep is usually all that it needs to reset. 2) The furnace may be struggling to stay lit due to too low of gas pressure from the gas supply valve that shuts off prematurely. The TSTAT may detect this and go into a “Leak Detection Mode” for 30 seconds. 3) Finally, there might be something malfunctioning near the thermostat that is causing interference.