Rheem RGPH-07EAMGR Error Code 4 Blinks (2-sec pause): Pressure Switch Shorted
What Does Code 4 Blinks (2-sec pause) Mean?
A 4-blink pattern on the Rheem RGPH-07EAMGR's OK LED indicates that the pressure switch is shorted — stuck in the closed position when the control board expects it to be open. Before starting the induced draft motor, the board verifies the pressure switch is open to confirm a safe starting condition. If the switch is already closed, the board will not proceed.
The pressure switch is a safety device that verifies combustion gases are being properly vented through the exhaust. Under normal operation, the switch is open when the inducer motor is off and closes when the inducer creates sufficient negative pressure (draft). A switch stuck in the closed position defeats this safety verification.
The most common cause is a defective pressure switch with contacts that have mechanically stuck or welded together. Water or moisture in the pressure switch housing or the sensing hose can also hold the diaphragm in the closed position. Less commonly, a wiring short between the pressure switch terminals can simulate a closed switch. A technician should test the switch and replace it if the contacts do not open properly.
Common Causes
When to Call a Professional
Contact a licensed HVAC technician if:
- The furnace will not start and the OK LED blinks 4 times
- The pressure switch area shows signs of moisture or condensation
- The switch was recently exposed to water from a condensate backup
✓ Verified against manufacturer service manual — March 2026