HVACopediaLennox · Furnace
E345 Relay O failure
What the control is telling you
Listed in the 107045-XX table as an O relay failure; no action text given. The manual (including its troubleshooting section) gives no corrective procedure for this code; steps are general checks only.
Applies to: EL296UHV(X) series furnaces with integrated control 107045-XX only
Likely causes
- O relay failure on integrated control
Test and repair steps
- Check wiring at the O terminal and on-board link W951 (R to O) configuration for dual-fuel/heat pump use.
- If wiring and configuration are correct, suspect the integrated control; this manual gives no further procedure.
Settings for these units
Recommended filter size by cabinet width · EL296UHV
| Cabinet width | Side return | Bottom return |
|---|---|---|
| 17-1/2 in. | 16 x 25 x 1 in. (1) | 16 x 25 x 1 in. (1) |
| 21 in. | 16 x 25 x 1 in. (1) | 20 x 25 x 1 in. (1) |
| 24-1/2 in. | 16 x 25 x 1 in. (2) | 24 x 25 x 1 in. (1) |
Number in brackets is the quantity of filters.
Filters are field supplied and installed outside the furnace; inspect monthly.
Recommended filter size by cabinet width · Lennox SL280UHV
| Cabinet width | Side return | Bottom return |
|---|---|---|
| 14-1/2 in. | 16 x 25 x 1 in. (1) | 14 x 25 x 1 in. (1) |
| 17-1/2 in. | 16 x 25 x 1 in. (1) | 16 x 25 x 1 in. (1) |
| 21 in. | 16 x 25 x 1 in. (1) | 20 x 25 x 1 in. (1) |
| 24-1/2 in. | 16 x 25 x 1 in. (2) | 24 x 25 x 1 in. (1) |
Number in brackets is filter quantity; filters are field supplied.
Never run the unit without a filter installed.
Models that show this code
18 models in EL296UHV, Lennox SL280UHV
Other codes on the same units
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Source: Lennox EL296UHV(X) Unit Information / Service Literature, Ignition Control 107045-XX Diagnostic Codes table, p.44. Summarized in our own words; check the original manual for your model.
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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.