What It Means
- CBK45UHPT, CBK45UHVT: Sensor communications issue
- Locked Rotor
- EL18KSLV: Communication abnormal with compressor drive module
Lennox Split & Multi-Split
Lennox Split & Multi-Split Error Code 4
Split & Multi-Split
4 means different things on different Split & Multi-Split models. Enter your model number to see only your reading, or find your model below.
Causes & actions from Lennox
Sensor communications issue
Models: CBK45UHPT, CBK45UHVT
Air handler (indoor)
How it shows
- rds noncomm red flash led: 4 (red: flashing ×4)
Check sensor connection. Ensure connection is clean and tight.
Other manual wording (1 of 2)
CBK45UHVT
Check sensor connec- tion. Ensure connection is clean and tight.
Other manual wording (2 of 2)
CBK45UHPT
Check sensor connec- tion. Ensure connec- tion is clean and tight.
Applicable models & manual sources
- CBK45UHPT
Sensor communications issue
- CBK45UHVT
Sensor communications issue
- CBK45UHVT
Sensor communications issue
- CBK45UHVT
Sensor communica- tions issue
- CBK45UHVT
Sensor communica- tions issue
- CBK45UHPT
Sensor communica- tions issue
Locked Rotor
4 models
HSXB15, XC15, XP15, XP19
How it shows
- lsom alert led: 4 (alert: flashing ×4)
1Run capacitor has failed. 2Low line voltage (contact utility if voltage at disconnect is low). (cid:4) Check wiring connections 3Excessive liquid refrigerant in the compressor. 4Compressor bearings are seized.
Other manual wording (1 of 2)
XC15, XP15
1Run capacitor has failed. 2Low line voltage (contact utility if voltage at disconnect is low). 3Excessive liquid refrigerant in the compressor. 4Compressor bearings are seized.
Other manual wording (2 of 2)
HSXB15
1 Run capacitor has failed. 2 Low line voltage (contact utility if voltage at disconnect is low). 3 Excessive liquid refrigerant in the compressor. 4 Compressor bearings are seized.
Applicable models & manual sources
- XP19
Locked Rotor
- XP19
Locked Rotor
- XC15
Locked Rotor
- XP15
Locked Rotor
- HSXB15
Locked Rotor
Communication abnormal with compressor drive module
Models: EL18KSLV
Heat pump (outdoor)
How it shows
- el18kslv outdoor fault display: 4
- el18kslv pcb fault led: 4
Communication abnormal between main control board and compressor drive module
Applicable models & manual sources
- EL18KSLV
Communication abnormal with compressor drive module
Disclaimer: This information is for general reference. Code wording and instructions vary by model. Always follow the service manual for your exact unit.
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