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Lennox · Furnace

E203 Unit capacity not programmed

Critical severity EL296UHVLennox SL280UHVLennox SL297NV

What the control is telling you

No valid unit size (capacity) code is programmed; at power-up the display shows three horizontal bars followed by continuous E203. Critical alert.

Applies to: EL296UHV(X) series furnaces (integrated control 103130-XX and 107045-XX)

Likely causes

  • Replacement control not programmed
  • Invalid unit code

Test and repair steps

  1. Make sure the control is idle (no heat, cool or fan) and set the room thermostat to OFF.
  2. Hold the diagnostic button until a solid P appears, then release; P starts blinking.
  3. Press and hold again; the control shows each unit size code for 3 seconds. Release on the correct code: 0=045V36B, 1=070V36B, 2=090V36C, 3=090V48C, 4=090V60C, 5=110V48C, 6=110V60C, 7=135V60D.
  4. While the selected code flashes (10 seconds), press and hold for 5 seconds; the control stores it and resets.
  5. If the 10 seconds run out or the button is held less than 5 seconds, nothing is saved; repeat.
  6. Cycle 24 V power to verify: the display should show the unit size code at power-up; three bars means it is still not recognized.
  7. Field replacement controls may need this manual configuration.

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Source: Lennox EL296UHV(X) Unit Information / Service Literature, Table 5 Ignition Control 103130-XX Diagnostic Codes, p.34; Ignition Control 107045-XX Diagnostic Codes table, p.41, Program Unit Capacity Size Mode p.109. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.