Lennox EL296UHV Error Code E 228: Combustion Air Inducer Calibration Failure
What Does Code E 228 Mean?
Error code E228 on the Lennox EL296UHV means a combustion air inducer calibration failure: the control was unable to perform its pressure-switch calibration. Because the EL296UHV is a two-stage furnace with both a low and a high pressure switch and an inducer that changes speed between firing rates, the SureLight control periodically calibrates how the switches respond to inducer speed so it knows what draft to expect at each stage. If that routine cannot complete, the board posts E228 and holds off ignition.
Calibration relies on the pressure switches reacting predictably as the inducer changes speed. If a switch does not respond as expected — because of loose or corroded wiring connections, cracked or disconnected tubing, condensate in a hose, a vent restriction, or a switch not seating properly — the control cannot establish valid reference points and the calibration fails. Rather than fire with reference data it cannot trust, the furnace stops.
E228 concerns the calibration process itself rather than a single switch state like E223 or E225. If calibration keeps failing, the board can escalate into E276, a watchguard calibration lockout that forces a timed wait before retrying, and it can appear alongside pressure-switch retry codes such as E271. The error clears once calibration succeeds on a later attempt.
What You'll Notice
- The furnace does not attempt to ignite, and the display shows E228
- The seven-segment display shows E228 after a call for heat
- The inducer may run without the burners ever lighting
- The fault can persist through several attempts rather than clearing on its own
- Heat is unavailable until the calibration completes
How This Is Diagnosed
A technician checks the pressure-switch wiring and hose connections first, since loose terminals, cracked tubing, or condensate in a hose are common reasons calibration cannot establish valid readings. They confirm each switch is seated and responds as the inducer changes speed, and they inspect the vent system for restrictions that would skew the draft the control measures during calibration.
Using a manometer they read draft (in inches of water column) at the low- and high-fire inducer speeds to verify the inducer reaches its expected speeds and the switches trip at their rated points. If wiring, tubing, and venting are sound but calibration still fails, a pressure switch or the inducer may be at fault. This is diagnostic information only and is not a homeowner task.
When to Call a Professional
This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:
- The furnace will not attempt ignition and the display shows E228
- E228 returns after the furnace power is cycled
- The pressure-switch hoses or wiring look loose, cracked, or corroded
- E228 appears together with E276 (watchguard calibration lockout) or E271
- The inducer runs but the burners never light across repeated attempts
Frequently Asked Questions
What is pressure-switch calibration on this furnace?
It is a routine where the two-stage SureLight control learns how the low and high pressure switches respond as the inducer changes speed, so it knows what draft to expect at each firing rate. E228 means that routine could not complete.
Will E228 clear by itself?
It clears once calibration succeeds on a later attempt. If the underlying wiring, tubing, or vent issue remains, the code keeps returning and can escalate to the E276 watchguard calibration lockout until a technician corrects it.
Is E228 a dangerous fault?
It is rated lower severity because the furnace refuses to fire rather than run on unverified data. The concern is the wiring, tubing, or vent condition preventing calibration, which a technician should find and fix.
✓ Verified against manufacturer service manual — March 2026