Dometic E4 fault code — Thermostat
Applies to: Single Zone LCD thermostat, 3313192, 3313193, 3313194
What E4 means
The Dometic Single Zone LCD thermostat manual lists E4 as an open circuit or out-of-range outdoor temperature sensor on select models; heat pump operation locks out while air conditioner, fan, and furnace operation can continue.
Owner-safe checks
- Record the E4 code, selected mode, fan setting, setpoint, and outdoor temperature estimate.
- Use normal furnace or other installed backup heat controls if the heat pump locks out and the RV needs heat.
- Avoid repeated heat-pump retries if the E4 code returns.
Service-only work
- Outdoor temperature sensor and heat-pump control diagnosis should be handled by qualified RV HVAC service.
Safety boundary
Do not open thermostat, rooftop HVAC, or electrical compartments, and do not bypass communication or sensor circuits. Shut the affected HVAC system off and arrange qualified RV HVAC service for unresolved Single Zone LCD faults.
Official sources
Related symptom guides
- RV thermostat display shows LO, HI, or sensor code
- Dometic Single Zone LCD low-ambient heat-pump lockout
- Pre-service checklist for RV appliance calls