Lennox Error Code E155: Refrigerant leak sensor #2 communication lost (Furnace)
Lennox error code E155 on a furnace means: Refrigerant leak sensor #2 communication lost. It is also called Lennox diagnostic code E155.
Homeowner? What Lennox code E155 means for you
Call a technician Your furnace is reporting: Refrigerant leak sensor #2 communication lost. 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 E155 mean?
The control has lost communication with refrigerant detection sensor #2. The blower latches on for at least 5 minutes after communication returns.
Applies to: ML180UHEK (R-454B era) single-stage 80% furnaces with integrated control 107792-XX (ML180UH045/070/090/110/135, incl. low-NOx X models)
Common causes of Lennox code E155
- Damaged or unplugged sensor #2 harness or connector
- Sensor #2 damaged or plug obstructed
- LGWP2 enabled with no second sensor fitted
Lennox models that use code E155
ML180UH045E36AKML180UH045XE36AKML180UH070E36AKML180UH070E36BKML180UH070XE36AKML180UH070XE36BKML180UH090E48BKML180UH090E60CKML180UH090XE48BKML180UH110E60CKML180UH110XE60CKML180UH135E60DK
Other Lennox Furnace codes
All Lennox Furnace error codes →
Lennox code E155: homeowner questions
What does Lennox code E155 mean?
Refrigerant leak sensor #2 communication lost. The control has lost communication with refrigerant detection sensor #2. The blower latches on for at least 5 minutes after communication returns.
Is it safe to keep using my furnace with code E155?
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 E155 myself?
You can try one reset (power off for 30 seconds, then on). If Lennox code E155 comes back, the cause is still there and a licensed technician should check it.
Who can fix Lennox code E155 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
Troubleshooting guides
- Blowing cold air All brands · Furnace
- No heat All brands · Furnace
- Short cycling All brands · Furnace
- Blower motor does not run - Lennox SL280UHV ECM checks Lennox · Furnace
- Display shows two horizontal bars (soft disable) - Lennox SL297NV Lennox · Furnace
- Furnace will not run (no heat) - Lennox EL195UHNE Lennox · Furnace
- Furnace will not run (no heat) - Lennox SL297NV Lennox · Furnace
- Furnace will not run - Lennox SL280UHV checklist Lennox · Furnace
- Indoor blower does not run - Lennox EL195UHNE Lennox · Furnace
- Indoor blower does not run - Lennox ML180UHE Lennox · Furnace
- Poor ignition or combustion resonance - Lennox EL195UHNE Lennox · Furnace
- Poor ignition or loud combustion resonance - Lennox SL280UHNV Lennox · Furnace
- Two horizontal lines on display (soft disable) - Lennox communicating Lennox · Furnace
Source: Lennox ML180UHEK Unit Information 100161/100166, Table 6 Integrated Diagnostic Codes, p.14; Table 17, p.33. 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.