| E0 | Lennox HVAC Error Code E0: How to Fix It | medium | Easy |
| E10 | Lennox HVAC Error Code E10: How to Fix It | medium | Medium |
| E11 | Lennox HVAC Error Code E11: How to Fix It | high | Medium |
| E12 | Lennox HVAC Error Code E12: How to Fix Compressor Inlet Over Current | medium | Medium |
| E13 | Lennox HVAC Error Code E13: How to Fix It | medium | Medium |
| E14 | Lennox HVAC Error Code E14: How to Fix It | high | Hard |
| E15 | Lennox HVAC Error Code E15: How to Fix It | medium | Medium |
| E16 | Lennox HVAC Error Code E16: How to Fix It | medium | Medium |
| E17 | Lennox HVAC Error Code E17: How to Fix It | medium | Medium |
| E18 | Lennox HVAC Error Code E18: How to Fix It | medium | Medium |
| E19 | Lennox HVAC Error Code E19: How to Fix It | medium | Medium |
| E2 | Lennox HVAC Error Code E2: How to Fix Low Pressure Switch Fault | medium | Medium |
| E20 | Lennox HVAC Error Code E20: How to Fix It | medium | Medium |
| E200 | Lennox Furnace Error Code E200: How to Fix It | critical | Hard |
| E200 | Lennox HVAC Error Code E200: How to Fix It | high | Medium |
| E201 | Lennox Furnace Error Code E201: How to Fix It | high | Medium |
| E201 | Lennox HVAC Error Code E201: How to Fix It | high | Medium |
| E202 | Lennox Furnace Error Code E202: How to Fix It | high | Medium |
| E202 | Lennox HVAC Error Code E202: How to Fix It | high | Medium |
| E21 | Lennox HVAC Error Code E21: How to Fix It | medium | Medium |
| E22 | Lennox HVAC Error Code E22: How to Fix It | medium | Medium |
| E223 | Lennox Furnace Error Code E223: How to Fix It | high | Medium |
| E223 | Lennox HVAC Error Code E223: How to Fix It | high | Easy |
| E227 | Lennox Furnace Error Code E227: How to Fix It | high | Medium |
| E227 | Lennox HVAC Error Code E227: How to Fix It | critical | Medium |
| E228 | Lennox Furnace Error Code E228: How to Fix It | high | Medium |
| E23 | Lennox HVAC Error Code E23: How to Fix It | medium | Medium |
| E24 | Lennox HVAC Error Code E24: How to Fix It | medium | Medium |
| E240 | Lennox Furnace Error Code E240: How to Fix It | high | Medium |
| E25 | Lennox HVAC Error Code E25: How to Fix It | medium | Easy |
| E250 | Lennox Furnace Error Code E250: How to Fix It | medium | Medium |
| E26 | Lennox HVAC Error Code E26: How to Fix Humidity Sensor Fault | medium | Medium |
| E27 | Lennox HVAC Error Code E27: How to Fix It | medium | Medium |
| E270 | Lennox Furnace Error Code E270: How to Fix It | medium | Medium |
| E270 | Lennox HVAC Error Code E270: How to Fix It | high | Easy |
| E271 | Lennox HVAC Error Code E271: How to Fix It | critical | Hard |
| E274 | Lennox Furnace Error Code E274: How to Fix It | medium | Medium |
| E274 | Lennox HVAC Error Code E274: How to Fix It | high | Medium |
| E28 | Lennox HVAC Error Code E28: How to Fix It | medium | Medium |
| E29 | Lennox HVAC Error Code E29: How to Fix It | medium | Medium |
| E290 | Lennox Furnace Error Code E290: How to Fix It | critical | Medium |
| E292 | Lennox Furnace Error Code E292: How to Fix It | critical | Medium |
| E292 | Lennox HVAC Error Code E292: How to Fix It | medium | Medium |
| E293 | Lennox HVAC Error Code E293: How to Fix It | medium | Medium |
| E3 | Lennox HVAC Error Code E3: How to Fix High Pressure Switch Fault | high | Medium |
| E30 | Lennox HVAC Error Code E30: How to Fix It | medium | Medium |
| E300 | Lennox Furnace Error Code E300: How to Fix It | critical | Medium |
| E31 | Lennox HVAC Error Code E31: How to Fix It | medium | Medium |
| E310 | Lennox Furnace Error Code E310: How to Fix It | high | Medium |
| E311 | Lennox Furnace Error Code E311: How to Fix It | high | Medium |
| E32 | Lennox HVAC Error Code E32: How to Fix It | medium | Medium |
| E33 | Lennox HVAC Error Code E33: How to Fix It — Ignition Lockout | high | Medium |
| E332 | Lennox Furnace Error Code E332: How to Fix It | critical | Hard |
| E34 | Lennox HVAC Error Code E34: How to Fix It | medium | Medium |
| E35 | Lennox HVAC Error Code E35: How to Fix It | medium | Medium |
| E36 | Lennox HVAC Error Code E36: How to Fix It | high | Medium |
| E37 | Lennox HVAC Error Code E37: How to Fix It | medium | Medium |
| E38 | Lennox HVAC Error Code E38: How to Fix It | medium | Medium |
| E380 | Lennox HVAC Error Code E380: How to Fix It | medium | Medium |
| E381 | Lennox HVAC Error Code E381: How to Fix It | medium | Medium |
| E39 | Lennox HVAC Error Code E39: How to Fix It | medium | Medium |
| E4 | Lennox HVAC Error Code E4: How to Fix It | medium | Medium |
| E40 | Lennox HVAC Error Code E40: How to Fix It | high | Hard |
| E41 | Lennox HVAC Error Code E41: How to Fix It | medium | Medium |
| E411 | Lennox HVAC Error Code E411: How to Fix It | critical | Medium |
| E413 | Lennox HVAC Error Code E413: How to Fix It | high | Hard |
| E415 | Lennox HVAC Error Code E415: How to Fix It | high | Medium |
| E419 | Lennox HVAC Error Code E419: How to Fix It | critical | Hard |
| E42 | Lennox HVAC Error Code E42: How to Fix It | medium | Medium |
| E420 | Lennox HVAC Error Code E420: How to Fix It | critical | Medium |
| E421 | Lennox HVAC Error Code E421: How to Fix It | high | Hard |
| E423 | Lennox HVAC Error Code E423: How to Fix It | high | Medium |
| E43 | Lennox HVAC Error Code E43: How to Fix Communication Fault | medium | Medium |
| E430 | Lennox HVAC Error Code E430: How to Fix It | high | Medium |
| E44 | Lennox HVAC Error Code E44: How to Fix It | medium | Medium |
| E45 | Lennox HVAC Error Code E45: How to Fix It | medium | Hard |
| E46 | Lennox HVAC Error Code E46: How to Fix It | medium | Medium |
| E47 | Lennox HVAC Error Code E47: How to Fix It | critical | Medium |
| E5 | Lennox HVAC Error Code E5: How to Fix It | medium | Medium |
| E6 | Lennox HVAC Error Code E6: How to Fix It | medium | Medium |
| E600 | Lennox HVAC Error Code E600: How to Fix It | high | Medium |
| E601 | Lennox HVAC Error Code E601: How to Fix It | high | Medium |
| E605 | Lennox HVAC Error Code E605: How to Fix It | high | Medium |
| E610 | Lennox HVAC Error Code E610: How to Fix It | high | Medium |
| E625 | Lennox HVAC Error Code E625: How to Fix It | medium | Medium |
| E7 | Lennox HVAC Error Code E7: How to Fix It | high | Medium |
| E8 | Lennox HVAC Error Code E8: How to Fix It | medium | Medium |
| E9 | Lennox HVAC Error Code E9: How to Fix It | medium | Medium |