Lennox Error Code Reference — All 28 Codes
Complete Lennox error code cheat sheet. All 28 fault codes with plain-English explanations and direct links to fix guides.
Use this page when your Lennox furnace, air conditioner, heat pump, or mini split is flashing a fault. Start with the exact code, then open the fix guide to diagnose airflow, ignition, sensor, pressure switch, board, or communication problems before you order parts or book a service call.
Tip: search the exact brand, model, and code together, for example "Lennox error code 13" or "Lennox pressure switch fault".
| Error Code | What It Means | Often a cheap fix? | Guide |
|---|---|---|---|
| Best Furnace Igniter Replacement | Universal and Brand-Specific Picks | — | Fix → |
| Lennox EL296V Error Codes | Variable-Speed Furnace Diagnostic Guide | — | Fix → |
| Lennox Error Code 114 | Causes & Fix | — | Fix → |
| Lennox Error Code 125 | Causes & Fix | — | Fix → |
| Lennox Error Code 224 | HSI Relay Failure Fix | — | Fix → |
| Lennox Error Code 240 | Ignitor Failed Fix | — | Fix → |
| Lennox Error Code 270 | Flame Signal Lost Fix | — | Fix → |
| Lennox Error Code 292 | Ignition Failure Fix | — | Fix → |
| Lennox Error Code 327 | Causes & Fix | — | Fix → |
| Lennox Error Code 412 | Limit Switch Fault Fix | — | Fix → |
| Lennox Error Code 434 | Outdoor Unit Communication Fault | — | Fix → |
| Lennox Error Code 441 | Limit Device Fault | — | Fix → |
| Lennox Furnace Error Codes | Complete Reference Guide | — | Fix → |
| Lennox Furnace Igniter Not Working | Causes & Fix | — | Fix → |
| Lennox G60UHV Furnace Error Codes | Flash Code Diagnostic Guide | — | Fix → |
| Lennox Harmony III Zoning System Error Codes | Complete Guide | — | Fix → |
| Lennox Healthy Climate Error Codes | Complete Guide | — | Fix → |
| Lennox iComfort EFO Error Code | Excessive Flame Out and Common iComfort Faults | — | Fix → |
| Lennox iComfort Error Code 225 | Communication Fault Fix Guide | — | Fix → |
| Lennox iComfort Error Code 31 | Pressure Switch Fault Diagnosis and Fix | — | Fix → |
| Lennox ResolvePlus Rooftop Unit Error Codes: Complete Guide | Lennox ResolvePlus RTU error codes and fault diagnostics. Covers flash codes, communicating system faults, and technician-level troubleshooting. | — | Fix → |
| Lennox Rooftop Unit Error Codes: Technician Guide | Complete Lennox RTU error code guide for LGH, LCH, and Strategos series. Flash codes, alphanumeric faults, and technician fixes for commercial rooftop units. | — | Fix → |
| Lennox SL280UHV Error Codes | Complete Fault Code Diagnostic Guide | — | Fix → |
| Lennox SLP98V Error Codes | Variable-Speed Furnace Fault Guide | — | Fix → |
| Lennox XC16 Air Conditioner Error Codes | Fault Code Diagnostic Guide | — | Fix → |
| Lennox XC21 Error Codes | Diagnostic Guide and Fixes | — | Fix → |
| Lennox XP20 Heat Pump Error Codes | Full iComfort Fault Reference | — | Fix → |
| Lennox XP21 Heat Pump Error Codes | iComfort Fault Code Guide | — | Fix → |