What It Means
- Low Flame Signal - check flame sensor
- O23-5, OF23-5, OHR23-5: Cad cell resistance >1600 Ohms
Lennox Ducted Heating
Lennox Ducted Heating Error Code 4
Ducted Heating
4 means different things on different Ducted Heating models. Enter your model number to see only your reading, or find your model below.
Causes & actions from Lennox
Low Flame Signal - check flame sensor
7 models
EL195UH, EL195UHNE, EL196UHE, ML180UHE, ML180UHV, ML193UHE, ML196UHE
How it shows
- Integrated control red LED: 4
This manual entry does not list further causes or actions.
Applicable models & manual sources
- EL195UH
Low Flame Signal − check flame sensor
- EL195UHNE
Low Flame Signal - check flame sensor
- EL196UHE
Low Flame Signal - check flame sensor
- ML180UHE
Low Flame Signal - check flame sensor
- ML180UHV
Low Flame Signal - check flame sensor
- ML193UHE
Low Flame Signal - check flame sensor
- ML196UHE
Low Flame Signal - check flame sensor
Cad cell resistance >1600 Ohms
Models: O23-5, OF23-5, OHR23-5
Oil furnace (indoor)
How it shows
- oil r7184b cad cell test led: 4 (led1: flashing ×4)
This manual entry does not list further causes or actions.
Applicable models & manual sources
- O23-5
Cad cell resistance >1600 Ohms
O23-5, OHR23-5, OF23-5
Disclaimer: This information is for general reference. Code wording and instructions vary by model. Always follow the service manual for your exact unit.
What should you check next?
Continue in ACLogics with guided diagnosis for your equipment and symptoms.
