2 flashes
Pressure switch stuck closed
This code typically points to
- Not explicitly detailed in accessible legacy brochure snippet
Next checks to confirm
- Verify pressure switch is not closed at call start
- Inspect switch and circuit/wiring per applicable furnace service manual
Escalation
Furnace heat cycle inhibited until fault is corrected
Reset behavior
Clears when pressure-switch fault is corrected and control sees normal startup condition.
Urgent
Fix now