Goodman GMEC960803BN Error Code Red 6 Flashes: Pressure Switch Cycle Lockout
What Does Code Red 6 Flashes Mean?
Six red flashes on the Goodman GMEC960803BN control board indicate a pressure switch cycling lockout. During a single call for heat, the pressure switch opened and closed 5 times, triggering a safety lockout. This intermittent behavior means the furnace can initially establish draft but cannot maintain it consistently.
The most common cause is a partial restriction in the exhaust venting system. Unlike a complete blockage (which would produce a code-red-3 for pressure switch stuck open), a partial blockage allows the inducer to initially pull enough vacuum to close the switch, but wind gusts, condensation, or intermittent obstructions cause the draft to fluctuate enough to let the switch open momentarily.
Leaking pressure switch tubing is another frequent cause. If the rubber hose connecting the pressure switch to the inducer housing has a small crack or a connection that is not fully sealed, air can leak in and reduce the vacuum reading intermittently. A technician needs to inspect the full vent run and pressure switch tubing to find the source of the intermittent draft loss.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Excessive venting restriction | Most common | ✗ Call a pro → |
| Leaking pressure switch tubing | Most common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- The furnace locks out with 6 red flashes during heating
- The furnace starts and stops repeatedly before locking out
- The problem occurs more often during windy conditions
✓ Verified against manufacturer service manual — March 2026