Lennox Error Code 10 flashes: Watchguard – pressure switch opened 5 times in one heat demand (Furnace)
Lennox error code 10 flashes on a furnace means: Watchguard - pressure switch opened 5 times in one heat demand. It is also called Lennox diagnostic code 10 flashes.
Homeowner? What Lennox code 10 flashes means for you
Call a technician Your furnace is reporting: Watchguard - pressure switch opened 5 times in one heat demand. The furnace has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.
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.
- Make sure the furnace front door or panel is closed properly; many furnaces will not run with the door switch open.
- Look at the air filter. If it is grey and clogged, replace it; a blocked filter causes many shutdowns.
- Outside, make sure the intake and exhaust pipes or vent cap are not blocked by snow, ice, leaves or a nest.
- Check that the gas valve next to the furnace is open (handle in line with the pipe). Do not force it.
- 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 Lennox error code 10 flashes mean?
Pressure switch opened 5 times in one heat call, so the control is in a 1 hour lockout.
Applies to: EL195UHNE furnaces with ignition control 103217-03 or 107163-01 (red LED)
Common causes of Lennox code 10 flashes
- Intermittent vent restriction (wind, ice)
- Partially plugged condensate drain
- Loose/leaking switch hoses
A technician checks these and 1 other possible causes on site before replacing any part.
Lennox models that use code 10 flashes
EL195UH040NE36BEL195UH060NE36BEL195UH080NE48CEL195UH100NE60C
Other Lennox Furnace codes
All Lennox Furnace error codes →
Lennox code 10 flashes: homeowner questions
What does Lennox code 10 flashes mean?
Watchguard - pressure switch opened 5 times in one heat demand. Pressure switch opened 5 times in one heat call, so the control is in a 1 hour lockout.
Is it safe to keep using my furnace with code 10 flashes?
It depends on the cause. The furnace has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.
Can I reset Lennox code 10 flashes myself?
You can try one reset (power off for 30 seconds, then on). If Lennox code 10 flashes comes back, the cause is still there and a licensed technician should check it.
Who can fix Lennox code 10 flashes near me?
Aurora Star Tech Inc. repairs Lennox furnaces in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.
Homeowner help: Furnace Not Turning On: What to Check · Furnace Blinking Light: What the Flash Codes Mean
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Source: Lennox EL195UHNE Unit Information Corp 1801-L1 (rev 04/2024), Table 4 (103217-03) / Table 5 (107163-01) diagnostic codes, p.8-10. 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.