White-Rodgers 50A55 Flash Codes: What Each One Means

By Ray Bennett · Updated 2 October 2026 · 4 min read · Checked against the maker’s manual

White-Rodgers 50A55 Flash Codes: What Each One Means

Short answer

The White-Rodgers 50A55 is a universal replacement board fitted to many furnaces, and its light counts out a code before a two second pause. 1 flash is a lockout after failed lighting, 2 and 3 the pressure switch stuck closed or open, 4 an open limit, 5 an open rollout switch, 6 reversed power or a poor ground, 7 a weak flame signal.

The White-Rodgers 50A55 is a universal hot surface ignition control, a replacement board that ends up in furnaces of many brands. Its instructions include adapters for Amana, Goodman and Trane furnaces. Its light flashes a count, pauses for about two seconds, and repeats.

Everything on this page comes from White-Rodgers’ own installation instructions for the 50A55-843, published under Emerson. If your furnace has its own maker’s board rather than this one, that maker’s code label on the door is the one to read.

Before you start

What to carry: a torch and a pen. Ten minutes.

Gas or electric? A gas furnace control, for natural gas or propane.

How to count. White-Rodgers says each flash lasts about a quarter of a second and each pause about two seconds. Count the flashes between pauses.

One flash at power-up is normal. White-Rodgers says the light flashes once when the control first gets power.

Two patterns where you turn the gas off. Continuous flashing with no pause. White-Rodgers says the control has sensed flame when no flame should be present, with no call for heat. Turn the furnace and the gas off and call a technician.

5 flashes, the rollout switch. The rollout switch trips when flame comes out of the burner area. Find out why before resetting it: what a rollout switch is telling you. White-Rodgers also warns never to short terminals on the gas valve.

What the flashes mean

White-Rodgers' list, flash by flash. A steady light means the fault is inside the control itself.

Check 1Free, two minutes

Count and look it up

1 flash, system lockout. White-Rodgers says the control locks out after its ignition attempts fail to light the burner, or after the flame is lost too many times.

2 flashes, pressure switch stuck closed. The switch reads closed at a moment it should be open.

3 flashes, pressure switch stuck open. The switch does not close, so the control will not light.

4 flashes, open limit switch. The furnace has overheated, or the limit circuit is open.

6 flashes. White-Rodgers says the 115 volt power is reversed or the ground is improper.

7 flashes, low flame sense signal. The flame is there, but the sensor is barely seeing it.

On steady. White-Rodgers says a light that stays on means the failure is internal to the control, and the control must be replaced.

The checks that are yours

Check 2

Work the free checks

1 flash: the gas first. A lockout after failed lighting starts with gas: is the gas valve on the furnace on, and the shut-off valve on the line open? On propane, is there gas in the tank: why a furnace clicks but will not light.

3 flashes: the vent and the hoses. A pressure switch that will not close points at a blocked vent, a cracked or water-filled hose, or a failing inducer: the places a pressure switch fault hides.

4 flashes: airflow. Change the filter and open every register before anything else: why a furnace overheats and cuts out.

7 flashes: the flame sensor. A weak flame signal is most often a dirty sensor rod: how to clean a flame sensor safely.

No light at all: the fuse. White-Rodgers says the board’s only serviceable part is a 3 amp automotive fuse that protects the transformer from a short. Remove whatever caused the short first, then replace it with a 3 amp automotive fuse only.

Getting it out of lockout

White-Rodgers gives three ways out of a lockout, and the control resets itself after an hour anyway.

Check 3Free, five minutes

Reset once, then watch

At the thermostat. Turn the call for heat off for at least one second but less than 20 seconds, then back on. White-Rodgers says this does not reset the control if flame was sensed with the gas valve off.

At the power. Interrupt the 24 volt power to the control for at least one second. White-Rodgers adds that you may also need to reset the flame rollout switch.

By itself. After one hour in lockout, White-Rodgers says the control resets automatically.

Then watch one cycle. If it locks out again, the cause is still there and resetting again only repeats the failure.

When it needs a technician

Check 4

Know when to stop

Flame with no call for heat. A gas valve that may be letting gas through. Gas off and a technician.

2 flashes. A pressure switch stuck closed, or a wiring short to it.

6 flashes. Reversed polarity or a poor ground is electrical work at line voltage.

A steady light. The control has failed inside. White-Rodgers says the control is not field repairable, and to replace it with the exact model and dash number.

Questions people ask

What does 3 flashes mean on a White-Rodgers board?

The pressure switch is stuck open: it has not closed to prove the vent, so the control will not light. Check the vent, the hoses and the inducer.

What does 1 flash mean?

A system lockout. White-Rodgers says the control locks out after its ignition attempts fail or the flame is lost too many times. It resets itself after an hour.

What does 7 flashes mean?

A low flame sense signal. The burner lights, but the sensor is only just seeing the flame, most often because the sensor rod is dirty.

Why is the light on steady?

White-Rodgers says a steady light means the failure is inside the control, which is not field repairable and must be replaced.

How do I reset a White-Rodgers 50A55?

Turn the thermostat’s call for heat off for 1 to 20 seconds, or cut the 24 volt power for a second or more, or wait an hour for the automatic reset.

Does one flash at start-up mean a fault?

No. White-Rodgers says the light flashes once when the control powers up.

Sources: White-Rodgers (Emerson) installation instructions for the 50A55-843 universal integrated furnace control