Furnace displays E16, indicating a low voltage or power supply fault

Safety first: Electrical work can be hazardous. Turn off power at the breaker before opening junction boxes. If you are not trained, contact an electrician.

Steps:

• Check other loads: Verify if lights dim or other appliances on the same circuit behave abnormally. If so, the circuit may be overloaded.
• Inspect furnace power connections: At the furnace junction box, ensure all wire nuts and terminal screws are tight and free of corrosion.
• Dedicated circuit: Confirm the furnace is on a dedicated circuit as recommended. Remove non-essential loads from the same circuit.
• Measure voltage (if equipped): With a multimeter and proper training, measure line voltage at the furnace. If it is consistently below the range on the data plate, contact your utility or electrician.
• Reset controller: After correcting wiring or load issues, reset the Danfoss controller and monitor for recurrence of E16.