Run capacitor
Common no-start and weak-compressor failure point. Match the microfarad and voltage rating.
Goodman Furnace EE2 Error Code — What It Means
The Goodman EE2 error code appears on the communicating thermostat or control board display of newer Goodman furnaces using the ComfortNet or similar communicating control system. EE2 indicates a communication error — the furnace control board has lost communication with the system (typically the thermostat or the communicating system bus). Unlike the traditional blink codes, EE-series codes appear on digital displays and indicate a system-level control communication problem rather than a mechanical fault.
Common Causes
- Loose or damaged communication wiring — The low-voltage communication bus between the thermostat and the furnace control board has a loose terminal, broken wire, or damaged connector.
- Thermostat firmware or compatibility issue — A ComfortNet or communicating thermostat that has an incompatible firmware version or a failed communication chipset generates EE2 on the furnace.
- Control board communication fault — The furnace’s main control board has a failed communication circuit, preventing it from receiving valid data from the thermostat or outdoor unit.
- Power surge damage — A voltage spike (lightning, grid transient) can damage the low-voltage communication circuitry on either the thermostat or control board without damaging anything else.
Step-by-Step Fix
- Check thermostat wiring connections — Turn off the furnace breaker. Remove the thermostat from its base and inspect all wire connections. Re-seat any loose wires and confirm terminal screws are snug.
- Inspect furnace control board wiring — At the furnace, check the low-voltage terminal strip. Look for corroded terminals, loose wires, or a cracked connector on the communication port.
- Test communication wire continuity — With a multimeter, check continuity on each low-voltage wire between the thermostat and furnace. An open wire needs to be replaced.
- Power cycle the system — Cut all power (breaker and thermostat) for 5 minutes, then restore. Many EE2 faults after a power surge clear with a full system reset.
- Try a conventional wiring mode — If the thermostat supports it, switch to conventional (non-communicating) wiring mode as a test. If the furnace operates without EE2 in conventional mode, the communication chipset in the thermostat has failed.
Parts Often Needed
| Part | Notes |
|---|---|
| Communicating thermostat | Replace when thermostat communication circuit has failed |
| Furnace control board | Replace when board communication circuit fails and all wiring tests good |
| Low-voltage wiring (18/5 or 18/8) | Replace if wire continuity test shows any open conductors |
Technician Tips
Goodman furnaces use a simple LED flash system on the control board. The diagnostic LED is usually visible through the blower compartment window. Count the flashes between pauses — that’s your error code. One flash = normal operation. Two flashes = pressure switch fault. Three flashes = limit switch. Four flashes = flame sensor. Goodman flame sensors are notorious for carbon buildup — cleaning with emery cloth every 2-3 years prevents most lockout calls. The control board on GMS8 and GMSS9 models is particularly sensitive to voltage fluctuations — if you see multiple different codes, check the transformer output (should be 24VAC ±10%).
Prevention: Install a whole-house surge protector on the furnace circuit to prevent board damage from power spikes.
Need Replacement Parts?
Before ordering, match the furnace part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Pro
If EE2 persists after replacing the thermostat and all wiring tests good, the furnace control board’s communication circuit has failed. Board replacement on newer communicating Goodman systems requires verifying firmware compatibility between the new board and the existing thermostat.