HTP Error Code FOU: Outdoor sensor fault (Boiler)
HTP error code FOU on a boiler means: Outdoor sensor fault. It is also called HTP diagnostic code FOU.
Homeowner? What HTP code FOU means for you
Usually minor Your boiler is reporting: Outdoor sensor fault. This code is usually informational or minor. The safe checks below often clear it; call us if it keeps showing up.
Safe things you can check yourself
- Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
- Make sure the unit has power: its on/off switch (often looks like a light switch near the unit) is ON and the breaker in the electrical panel is not tripped.
- Look at the pressure gauge on the boiler. If it reads much lower than usual or near zero, or water is leaking, call a technician.
- Outside, make sure the intake and exhaust pipes or vent cap are not blocked by snow, ice, leaves or a nest.
- Check that the boiler gas valve is open (handle in line with the pipe).
- Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.
Call (647) 657-2977Book a service call
Licensed technicians serving Vaughan, Toronto and the GTA.
What does HTP error code FOU mean?
Outdoor sensor is shorted, open, or the outdoor temperature is below -40 F. Boiler keeps running and ignores outdoor reset, using the programmed boiler temperature.
Applies to: EL-80, EL-110, EL-150, EL-220, EL-299, EL-399 (N/LP)
Common causes of HTP code FOU
- Outdoor sensor wiring damaged or shorted
- Sensor defective
HTP models that use code FOU
EL-80 LPEL-80 NEL-110 LPEL-110 NEL-150 LPEL-150 NEL-220 LPEL-220 NEL-299 LPEL-299 NEL-399 LPEL-399 N
Other HTP Boiler codes
HTP code FOU: homeowner questions
What does HTP code FOU mean?
Outdoor sensor fault. Outdoor sensor is shorted, open, or the outdoor temperature is below -40 F. Boiler keeps running and ignores outdoor reset, using the programmed boiler temperature.
Is it safe to keep using my boiler with code FOU?
Usually yes. Code FOU is normally minor, but if it keeps coming back have it checked.
Can I reset HTP code FOU myself?
You can try one reset (power off for 30 seconds, then on). If HTP code FOU comes back, the cause is still there and a licensed technician should check it.
Who can fix HTP code FOU near me?
Aurora Star Tech Inc. repairs HTP boilers in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.
Homeowner help: Boiler Not Heating: What to Check
Troubleshooting guides
- Condensing/corrosion of conventional boiler All brands · Boiler
- No heat or some zones cold All brands · Boiler
- Noise All brands · Boiler
- Poor heat / circulation All brands · Boiler
- Relief valve weeps every cycle / pressure climbs All brands · Boiler
- Short cycling / wasted fuel All brands · Boiler
- Symptoms of air in system All brands · Boiler
- Uneven heating All brands · Boiler
- Won't fire All brands · Boiler
- Boiler overheating lockout (F00, F05, F06) HTP · Boiler
- Cascade set-up HTP · Boiler
- Check thermostat circuit for stray voltage HTP · Boiler
- False flame signal with burner off (F11) HTP · Boiler
- Fan speed error (F13) HTP · Boiler
- Flame drops out while running (F10) HTP · Boiler
- Lockout on ignition (F09, no flame) HTP · Boiler
- Menu access codes HTP · Boiler
- Pump service mode to purge air HTP · Boiler
- Read fault history HTP · Boiler
- Reset a lockout HTP · Boiler
- Reset the maintenance reminder HTP · Boiler
- Start-up combustion and gas checks HTP · Boiler
- Test mode (fixed-fire, gas pressure and combustion) HTP · Boiler
- Thermostat calling but boiler not firing HTP · Boiler
Source: Elite EL-80 N Installation Manual (LP-293), p. 67. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.