Thermostat displays E13 and indicates W1/W2 heating output fault; furnace may not fire or may lock out

Safety first: Turn off power to the furnace at the service switch and breaker before working on wiring.

Steps to troubleshoot E13 heating output fault:

• 1. Inspect low-voltage fuse: Check the Goodman furnace control board for a blown 3–5A fuse. Replace if blown, but investigate for shorts on W1/W2 circuits.
• 2. Verify W wiring: Confirm that W1 (and W2 if used) are correctly connected at the thermostat and furnace control board. Look for loose or corroded connections.
• 3. Test thermostat output: With a call for heat active, measure 24VAC between W1 and C at the furnace control board. If no voltage is present, suspect the thermostat or wiring.
• 4. Bypass thermostat: Temporarily jumper R to W1 at the furnace control board. If the furnace starts and runs normally, the thermostat's W1 output is likely defective.
• 5. Confirm staging setup: Ensure the thermostat is configured for the correct number of heat stages to match the Goodman furnace (single-stage, two-stage, etc.). Incorrect staging can cause control errors.
• 6. Replace thermostat if needed: If wiring and configuration are correct but the thermostat never energizes W1/W2, replace the thermostat.