Lennox E228: combustion air inducer calibration failure

Furnace control display or LED

E228

“Combustion air inducer calibration failure”

SL280*V, SL280*NV, SL297*NV, EL296*V, EL297*V, EL297*E · 508559-01 p. 30; 508561-01 p. 37; 508585-02 p. 50; 1126-L5 p. 17; 508583-01 p. 53; 508577-02 p. 44
Technician

What it means

E228 means the furnace control could not perform its pressure switch calibration. The tables for the SL280, SL297, EL296*V and EL297 series call the code “Combustion air inducer calibration failure”; the action says the control was unable to perform the pressure switch calibration and asks the technician to check the vent system and the pressure switch wiring connections. The furnace resumes normal operation once the fault clears 508585-02, p. 50. The tables for the SLP98, SLP99 and G71MPP, including the 2025 and 2026 SLP99DFVK instructions, word the code itself as “Unable to perform successful pressure switch calibration.”. Their action starts with a retry after 300 seconds and gives the same two checks 508589-01, p. 44; 508589-02, p. 46.

When calibration keeps failing, the tables have a second code, E276: “Watchguard calibration failure.” with a 1-hour soft lockout that clears when calibration has finished successfully 1126-L5, p. 18, or on the SLP99DFVK “Soft lockout - Exceeded maximum number of calibration retries.” 508589-02, p. 47.

Lennox’s thermostat alert 228 is “GF Inducer Calibration Issue”, priority Service Soon: the furnace control is not able to calibrate the pressure switch. It clears automatically after a successful calibration 100017, p. 21. Lennox’s documents do not say that alert 228 and display code E228 report the same event.

Check these first

Lennox’s owner’s manuals have no code table and give no steps for E228. What they give is a general list for a unit that will not operate, to work through before calling a Lennox service technician. In the SLP99DFVK manual the order is:

Check that the electrical disconnect switches are ON 508590-01, p. 5.
Check the room thermostat for proper setting 508590-01, p. 5.
Replace any blown fuses or reset circuit breakers 508590-01, p. 5.
Check that the gas valve is ON 508590-01, p. 5. Its switch is behind the outer access panel; the manual’s gas valve steps set the thermostat to the lowest setting and turn off all electrical power to the unit before that panel comes off, and the switch is moved by hand only, never with tools 508590-01, p. 4.
Check that the air filter is not plugged, which would limit air flow 508590-01, p. 5. The SLP99DFVK manual says its filters are installed external to the unit, should be inspected monthly, and that a filter must be in place when the unit is operating 508590-01, p. 4. Before any service or maintenance, it says to turn the electrical power to the unit OFF at the disconnect switch 508590-01, p. 2.
Check that gas is turned on at the meter 508590-01, p. 5.
Check that the manual main shut-off valve is open 508590-01, p. 5.

Then record the model and serial number from the nameplate and call 508590-01, p. 5. The list is not tied to any code. More on it, and on how other Lennox manuals word it: owner checks before a service call.

The manual lists the annual inspection of the furnace venting system among the maintenance procedures that should only be conducted by a licensed professional service technician 508590-01, p. 5.

When to call a licensed technician

Checking the vent system and the pressure switch wiring connections 508585-02, p. 50.
The alert guide’s further checks for alert 228: blockage in the vent, the combustion air inducer, a blocked cold end heater box, condensate drain or drain strainers, cracked hoses, and whether the unit is level 100017, p. 21.
E276 appears 1126-L5, p. 18; 508589-02, p. 47.
The furnace still will not run after the checklist 508590-01, p. 5.
E228 keeps coming back after it clears. The owner’s manuals give no step for that; these pages send it to the technician.

Notes for different models

Series or document	Code	Wording	Source
SL280V, SL280NV, SL297NV, EL296V, EL297V, EL297E	E228	“Combustion air inducer calibration failure”	508585-02, p. 50; 1126-L5, p. 17; 508583-01, p. 53; 508577-02, p. 44
SLP98V, SLP99V, G71MPP	E228	“Unable to perform successful pressure switch calibration.” The action starts with a retry after 300 seconds.	508589-02, p. 46; 506610-01, p. 63; 506509-01, p. 66
EL296V, EL297V, SL280V, SL280NV, SL297*NV (some editions)	E276	“Watchguard calibration failure.”	1126-L5, p. 18; 1116-L4, p. 26; 508150-02, p. 48
SLP98V, SLP99V, G71MPP	E276	“Soft lockout - Exceeded maximum number of calibration retries.”	508589-02, p. 47; 506610-01, p. 63; 506509-01, p. 66
Lennox thermostat alert table	228	“GF Inducer Calibration Issue”, Service Soon	100017, p. 21

E228 is not in the E-code tables of the ML296, the ML297, the EL280E, the EL296E, or the K editions of the EL180, EL195, EL196, ML180, ML193 and ML196 for example 508521-01, pp. 41–44; 508907-01, pp. 45–48; 1901-L1, pp. 13–15; 1246-L10, pp. 12–14; 508569-01, pp. 44–46.