Ruud UGPH-07EAMGR Error Code 4 Blinks (2-sec pause): Pressure Switch Shorted
What Does Code 4 Blinks (2-sec pause) Mean?
Four blinks of the green "OK" status LED followed by a 2-second pause on the UTEC 1012-925 board mean the pressure switch is reading closed (shorted) at a time when it should be open — before the induced draft blower has built up any suction. At rest the switch should be open; the board only expects it to close after the draft motor starts. Seeing it already closed tells the board the safety proof is compromised, so it will not allow the burners to fire.
This is the counterpart to the 2-blink "pressure switch is open" code on the same board. Two blinks means the switch fails to close when it should — it cannot prove venting — while four blinks means the switch is stuck closed when it should be open at rest. Because the switch is a safety interlock that confirms proper exhaust venting, the board treats a stuck-closed switch as a fault rather than trusting it.
The overwhelming cause is a pressure switch whose internal contacts have welded or stuck closed; less commonly, shorted or damaged wiring between the switch and board makes the board read it as closed. Either way the fix is replacement of the failed part by a technician.
Do not bypass or jumper the pressure switch to force heat. It exists to stop the furnace from firing when exhaust is not venting properly, which is a carbon-monoxide safeguard — defeating it can let the furnace run while spilling combustion gases.
What You'll Notice
- The green status LED blinks four times, pauses about 2 seconds, then repeats
- The furnace will not start a heating cycle at all
- The failure is immediate — unlike the 2-blink code, the furnace does not spend 60 seconds trying to prove venting first
- No heat despite the thermostat calling for it
- The code persists regardless of weather or whether the outdoor vent is clear, because it is an internal switch or wiring fault rather than a blockage
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Stuck pressure switch contacts | Most common | ✗ Call a pro → |
| Shorted wiring to pressure switch | Uncommon | ✗ Call a pro → |
How This Is Diagnosed
A technician confirms the switch is genuinely stuck by checking continuity across it with the draft motor off — at rest it should read open. If it reads closed at rest, the switch is replaced.
If the switch itself tests open as it should, the tech inspects the wiring and connector between the switch and the control board for a short or a pinched wire. The board is only suspected after the switch and its wiring have been verified.
When to Call a Professional
This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:
- The furnace shows four blinks and will not start regardless of the vent condition
- The code appeared suddenly and does not change when you clear the outdoor vent
- Someone has previously jumpered or bypassed the pressure switch (have it corrected immediately)
- The four-blink code returns after the switch has been replaced
- Any time you are tempted to bypass the switch to restore heat
Frequently Asked Questions
What's the difference between 2 blinks and 4 blinks?
Two blinks means the pressure switch won't close, often from a blocked vent or weak draft. Four blinks means the switch is stuck closed when it should be open at rest — usually a failed switch that needs replacement.
Can I just jumper the pressure switch to get heat tonight?
No. The switch confirms your furnace is venting exhaust safely, and bypassing it can let the furnace run while spilling combustion gases, which is a carbon-monoxide hazard. Wait for the repair.
How much is a pressure switch replacement?
The switch itself is a modest-cost part, but the total depends on labor and your region, so get a local quote. It is a common, straightforward part for an HVAC technician to replace.
Sources
✓ Verified against manufacturer service manual — March 2026