What this code means
The official model-family manual identifies E348 as no 24-volt y2 output to c with a noncommunicating outdoor unit.
Safe checks
- Confirm the thermostat is on, set correctly, and calling for heating or cooling.
- Check the air filter and visible return-air path for obvious airflow restrictions.
- Record the displayed code or flash sequence before scheduling service.
First step
Record the code, check the thermostat and filter, and schedule service if the condition remains.
Frequently asked questions
What does E348 mean on a Lennox SLP99UH110XV60C*?
The official model-family manual identifies E348 as no 24-volt y2 output to c with a noncommunicating outdoor unit.
What should I safely check before scheduling service?
Use only the visible, non-invasive checks listed on this page. Do not open equipment panels.
When should GreenFlow handle this code?
Call GreenFlow if the code repeats, the equipment is locked out, heating or cooling is not restored, or the condition involves gas, ignition, pressure, wiring, a motor, or a control board.