What It Means
- OD EIM W External Miswire Fault
Lennox Equipment not specified
Lennox Error Code 421
Equipment not specified:
Causes & actions from Lennox
How it shows
- iComfort S30 alert: 421
Priority condition: Service Urgent The W output terminal on the outdoor unit is not wired correctly. Voltage sensed on W output terminal when Y1 out is deactivated.
Applicable models & manual sources
- iComfort S30
OD EIM W External Miswire Fault
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?
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