What causes Rheem Gas Furnace 57?

A blocked vent or air intake pipe outside, such as snow, ice, leaves, a nest or debris at the termination. Vent piping that is longer or has more elbows than the manual allows, which Rheem says can cause nuisance or erratic pressure switch operation. Water or moisture in the pressure switches or their hoses, often from a plugged condensate trap or drain on 90%+ furnaces. Strong wind at the vent termination, which Rheem notes can open a pressure switch. A cracked, kinked, loose or disconnected pressure switch hose. A faulty or intermittent high pressure switch, or a wiring problem between the switch and the control board. An inducer (induced draft motor) that is wired incorrectly or not moving enough air. A blocked heat exchanger.

How do I fix Rheem Gas Furnace 57?

Write down the code, and note whether it alternates with "h" or with 46. That tells your technician whether only the high-stage switch or both switches are open. Go outside and check the furnace's vent and air intake pipes. Clear any snow, ice, leaves or other blockage you can reach safely. Check the condensate drain line and trap for clogs or standing water, and make sure the drain hose isn't kinked. A furnace that can't drain can push water into the pressure switch hoses. With the furnace power off, look at the small rubber hoses running to the pressure switches. Reconnect any that have come loose and note any that are cracked, kinked or have water in them. If it's very windy, note that. Rheem's troubleshooting guide lists excessive wind as a cause of a pressure switch opening. Reset the furnace by turning the power off and back on. If code 57 comes back, call an HVAC technician. Don't bypass or jumper a pressure switch; it's a safety device that keeps the furnace from running without proper venting.

When should I call a pro for Rheem Gas Furnace 57?

Checking the pressure switches, their hoses and wiring, and checking for intermittent switch operation, as Rheem's troubleshooting guide directs. Checking the vent for blockage and comparing the vent length and number of elbows with the maximums in the furnace's installation manual. Clearing water from the switches and hoses and fixing the condensate trap or drain that let it in. Confirming the inducer is wired correctly and checking the heat exchanger for blockage. Replacing the high pressure switch only after the vent, drain and hoses check out.

Code: 57🔥 Rheem Gas Furnace

Rheem Furnace Code 57: High Pressure Switch Open (Meaning, Causes, Fixes)

Q: What does Rheem Gas Furnace 57 mean?

Code 57 on a two-stage Rheem or Ruud gas furnace means the high pressure switch is open when it should be closed. That switch proves the draft inducer is pulling enough air for high-stage heat, so the usual causes are a blocked or overly long vent, water in the pressure switch hoses or a plugged condensate drain, strong wind at the vent, or a bad switch or hose. Check the outside vent and the condensate drain first; pressure switch testing belongs to a technician. Rheem's fault code label for its serial communicating gas furnaces lists 57 as "High Pressure Switch Open" under pressure switch faults, and the R96T installation manual's fault code table and troubleshooting guide list it as "High Pres. Switch Open." These furnaces have two air-proving negative pressure switches, one for low stage and one for high stage. When a heat call starts, the inducer runs a 30-second prepurge on high stage and both switches must close before the gas valve opens. Code 57 means the high-stage switch didn't close or opened while it should be closed. If the high pressure switch is open when the thermostat calls for full heat, the manual says the display alternates between "h" (low-stage heat) and 57, so the furnace may keep heating on low stage only. If the low pressure switch is also open, the display alternates 46 and 57.

Reviewed 2026-10-23 · Based on 2 manufacturer & service sources

What the code means

Rheem's fault code label for its serial communicating gas furnaces lists 57 as "High Pressure Switch Open" under pressure switch faults, and the R96T installation manual's fault code table and troubleshooting guide list it as "High Pres. Switch Open." These furnaces have two air-proving negative pressure switches, one for low stage and one for high stage. When a heat call starts, the inducer runs a 30-second prepurge on high stage and both switches must close before the gas valve opens. Code 57 means the high-stage switch didn't close or opened while it should be closed. If the high pressure switch is open when the thermostat calls for full heat, the manual says the display alternates between "h" (low-stage heat) and 57, so the furnace may keep heating on low stage only. If the low pressure switch is also open, the display alternates 46 and 57.

Likely causes

A blocked vent or air intake pipe outside, such as snow, ice, leaves, a nest or debris at the termination
Vent piping that is longer or has more elbows than the manual allows, which Rheem says can cause nuisance or erratic pressure switch operation
Water or moisture in the pressure switches or their hoses, often from a plugged condensate trap or drain on 90%+ furnaces
Strong wind at the vent termination, which Rheem notes can open a pressure switch
A cracked, kinked, loose or disconnected pressure switch hose
A faulty or intermittent high pressure switch, or a wiring problem between the switch and the control board
An inducer (induced draft motor) that is wired incorrectly or not moving enough air
A blocked heat exchanger

Safe DIY checks

⚠ Before you start

Turn off power at the furnace/HVAC service switch and the breaker before opening panels. Shut the gas valve before any work near the burners, and never disconnect or alter the gas line. If you smell gas, leave the house and call your gas utility.

Write down the code, and note whether it alternates with "h" or with 46. That tells your technician whether only the high-stage switch or both switches are open.
Go outside and check the furnace's vent and air intake pipes. Clear any snow, ice, leaves or other blockage you can reach safely.
Check the condensate drain line and trap for clogs or standing water, and make sure the drain hose isn't kinked. A furnace that can't drain can push water into the pressure switch hoses.
With the furnace power off, look at the small rubber hoses running to the pressure switches. Reconnect any that have come loose and note any that are cracked, kinked or have water in them.
If it's very windy, note that. Rheem's troubleshooting guide lists excessive wind as a cause of a pressure switch opening.
Reset the furnace by turning the power off and back on. If code 57 comes back, call an HVAC technician. Don't bypass or jumper a pressure switch; it's a safety device that keeps the furnace from running without proper venting.

🛠 When to call a pro

Checking the pressure switches, their hoses and wiring, and checking for intermittent switch operation, as Rheem's troubleshooting guide directs.
Checking the vent for blockage and comparing the vent length and number of elbows with the maximums in the furnace's installation manual.
Clearing water from the switches and hoses and fixing the condensate trap or drain that let it in.
Confirming the inducer is wired correctly and checking the heat exchanger for blockage.
Replacing the high pressure switch only after the vent, drain and hoses check out.

Sources

Last reviewed 2026-10-23. Always confirm against the manual for your exact model number.