White-Rodgers 50M56X Error Codes: E01, E07, E24 and More

By Ray Bennett · Updated 2 October 2026 · 5 min read · Checked against the maker’s manual

White-Rodgers 50M56X Error Codes: E01, E07, E24 and More

Short answer

The White-Rodgers 50M56X universal furnace board shows its codes on a three character display. On is standby and ht is heating with a flame. E codes are faults: E01 the pressure switch open, E07 the rollout switch, E18 the high limit, E21 a lockout after the ignition tries ran out, and E24 a lockout on the pressure switch. It keeps up to five codes for 14 days.

The White-Rodgers 50M56X-843 is a universal replacement control for single stage gas furnaces. It goes in place of the original board on many brands, and White-Rodgers’ reference card says it replaces more than 550 part numbers. Instead of a blinking light, it has a three character display that spells out what it is doing.

Everything on this page comes from White-Rodgers’ own installation instructions for the 50M56X-843, published by Copeland, which now owns the brand. Because this board replaced your furnace’s original control, the chart on the furnace door was written for a different board. Use this list.

Before you start

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

Gas or electric? Gas, natural gas or propane, with a 120 volt hot surface igniter.

Check it is this board. 50M56X-843 is printed on the control. The older 50M56U has a blinking light instead: the 50M56U codes.

What power up looks like. White-Rodgers says the display shows 888 at power up, then dcF while it configures itself to the furnace for about 30 seconds, then On for standby.

Where you stop. E04: flame when there should be none. White-Rodgers says to check the gas valve works properly. Turn the gas off and call a technician.

E07: the rollout switch. It opens when flame comes out of the burner area. Find out why before anyone resets it: what a rollout switch is telling you.

E13 and E22: inside the control. White-Rodgers says an internal igniter relay failure or a gas valve relay error means replacing the control.

What the display means

The 50M56X spells out what it is doing. 888, dcF and On are the normal start, and ht with a flame current is normal heating.

Check 1Free, two minutes

Read the status codes

On. Standby, ready for a call from the thermostat.

htP, hpr, hIp, hPo. A call for heat before the purge, during the pre-purge, between tries, and during the post-purge. White-Rodgers adds that htP also shows when an error is stopping ignition.

Ign and tFI. The igniter warming up, and the trial for ignition.

ht. Heating with a flame. White-Rodgers says the display alternates it with the flame current, measured to a tenth of a microamp.

CL and CL1, FAn. Cooling, low stage cooling, and a call for the fan alone.

bOn. The blower running after a power cut during a call, to cool down.

FLo: low flame current. A warning. White-Rodgers says to check the flame and clean or replace the flame sensor: how to clean a flame sensor safely.

The error codes

Code	What White-Rodgers says
E00	Line frequency error or internal fault
E01	Pressure switch open
E04	Flame detected when none should be present
E06	Open fuse
E07	Rollout switch open
E09	Pressure switch stuck closed
E11, E12	Gas valve on error, gas valve off error
E13	Igniter relay fault inside the control
E14	Igniter open
E15	Grounding error
E16	Reversed line polarity
E17	Twinning error
E18	High limit switch open
E21	Lockout, ignition retries exceeded
E22	Lockout, gas valve relay error inside the control
E23	Lockout, recycles exceeded after flame loss
E24	Lockout, pressure switch open
E25, E31, E32	Housing pressure switch on condensing furnaces
E41	Automatic configuration or system component error
EC1	NFC connection error, power cycle and retry

The checks that are yours

The common 50M56X codes grouped by what they point at: the air path, the flame, the heat limits and the power.

Check 2

Work the owner checks

E01 and E24: the air path. White-Rodgers says to check the pressure switch, the inducer and the flue. Look at the vent outside for blockage: the places a pressure switch fault hides.

E18: the high limit. White-Rodgers says to check for an open or failed high limit and any auxiliary switches. Start with the filter: why a furnace overheats and cuts out.

E21 and E23: the flame. Ignition failed, or the flame kept going out. Check the gas is on, then the flame sensor, especially if FLo has been showing.

E06: the fuse. White-Rodgers says to find and repair the 24 volt fault, then replace the fuse. The 24 volt circuit includes the thermostat wires: what each thermostat wire does.

E14: the igniter. White-Rodgers’ answer is a new igniter.

E15 and E16: the wiring. Grounding and polarity are an electrician’s job.

Reading the history and resetting

Check 3Free, five minutes

Use the two buttons

Read the history. In standby, hold OPTION and SELECT together for two to five seconds. FLt appears, then the stored codes. Press OPTION for under a second to step to the next one. Eno means none are stored.

How much it keeps. White-Rodgers says up to five codes, stored for up to 14 days.

Clear the history. Hold both buttons for five to ten seconds until the display alternates CLr and FLt, then let go. CLr flashes three times when the codes are erased.

Reset a lockout. White-Rodgers says it resets itself after an hour in lockout, or you can remove the 24 volt power for more than 10 seconds.

After a new install. Some Trane, American Standard and York furnaces need the rollout bypass setting, or they show E07. White-Rodgers says the E41 code means wiring or a component needs checking before it configures. Both are for the installer.

Questions people ask

What does E01 mean on a White-Rodgers 50M56X?

The pressure switch is open. White-Rodgers says to check the switch, the inducer and the flue. A blocked vent outside is the first thing to look for.

What does E24 mean?

A lockout because the pressure switch stayed open. Fix the air path first, then reset by removing the 24 volt power for more than 10 seconds, or wait an hour.

What does FLo mean on my furnace display?

Low flame current. The furnace still runs, but White-Rodgers says to check the flame and clean or replace the flame sensor.

What does htP mean?

A call for heat before the pre-purge starts. White-Rodgers says it also shows when an error is stopping ignition, so look for an E code alongside it.

How do I see old codes on a 50M56X?

In standby, hold OPTION and SELECT for two to five seconds. The last codes play back, and Eno means there are none.

Why does it show dcF?

It is configuring itself to your furnace, which White-Rodgers says takes about 30 seconds at power up. On appears when it is done.

Sources: White-Rodgers (Copeland) installation instructions 0037-7827001 for the 50M56X-843 universal integrated single stage 120V hot surface ignition control kit, and the White-Rodgers furnace controls reference card R-4952