Rheem and Ruud furnace code 57: pressure switch open

Furnace control display or LED

57

“PRESS SWITCH STUCK OPEN WHEN SHOULD BE CLOSED”

(-)92P & (-)(-)92MSP, (-)92T & (-)(-)92MSX, (-)95P & (-)(-)95MSP, (-)95T & (-)(-)95MSX, (-)801S / (-)801P UPFLOW/HORIZONTAL & (-)(-)801MSS / (-)(-)801MSP; (-)(-)80MSS / 80MSP, (-)801S / (-)801P DOWNFLOW & (-)(-)80DSS / 80DSP, (-)801T UPFLOW/HORIZONTAL & (-)(-)80MSX, (-)801T DOWNFLOW & (-)(-)80DSX · 92-24161-118-16 p. 87; 92-24161-154-03 p. 87; 92-24161-111-17 p. 87; 92-24161-120-16 p. 87; 92-24161-142-15 p. 39; 92-24161-143-14 p. 34; 92-24161-144-09 p. 39; 92-24161-145-10 p. 34
Technician

What it means

57 means the furnace control expected a pressure switch to be closed while the inducer runs, and the switch was open. At each call for heat the control first checks that the pressure switch is open, then runs the induced draft blower (inducer) for a pre-purge; the negative pressure switch closes, and the gas valve opens for ignition after the 30-second pre-purge 801T: 92-24161-144-09, p. 38.

Which switch depends on the furnace. On single-stage furnaces the code list reads “PRESS SWITCH STUCK OPEN WHEN SHOULD BE CLOSED” 95P: 92-24161-111-17, p. 87; 801T: 92-24161-144-09, p. 39. On two-stage and communicating furnaces 57 is the high pressure switch, and the low pressure switch has its own codes, 45 and 46 96P: 92-24161-122-12, p. 88; 96V: 92-24161-124-12, pp. 117–118.

The fault card of the single-stage 95P describes what follows. Gas heat stops; other modes such as cooling should still work. The code appears only after the inducer has run at least ten seconds. Before ignition, the inducer stays on high for five minutes from the start of the pre-purge, stops, and the control tries again; this repeats until the switch closes or the call for heat ends. If the switch opens while the burners are lit, the control waits at least 2 seconds, switches off the gas valve relay, shuts the furnace down and goes back to proving the switch while the call for heat lasts 92-24161-111-17, pp. 92–93. The lockout section of the same manual describes the start-up case as a five-minute soft lockout when the low pressure switch (so worded) has not closed after 60 seconds of inducer operation, reset automatically after five minutes 92-24161-111-17, p. 95.

On two-stage and communicating furnaces, a 57 during high heat with the low pressure switch still closed drops the furnace to low fire, and it keeps running to try to satisfy the thermostat. If the thermostat is calling for full heat, the display then alternates h (low heat) and 57 96P: 92-24161-122-12, p. 96; 96V: 92-24161-124-12, pp. 92, 118.

When 45 and 57 alternate

When both the high and the low pressure switch are open and both should be closed, the communicating furnaces show 45 and 57 in turn, with the top segment of the right digit lit for ½ second between them 96V: 92-24161-124-12, p. 93; 802V: 92-24161-148-07, p. 45; 92-24161-149-06, p. 40; 97V: 92-24161-126-04, p. 76; 98V: 92-24161-159-03, p. 73. The first editions of the 96P and 96T manuals give the same condition as 46 and 57 92-24161-122-01, p. 88; 92-24161-157-00, p. 88. Their 2017 revisions list neither pair 92-24161-122-12, pp. 88–89. The 45 page covers the low pressure switch.

Check these first

Rheem’s owner’s manuals have no code list and no reset (92-20802-128-03; 92-20802-130-02). For a furnace that will not operate, the last of their operating instructions gives two steps 92-20802-128-03, p. 4; 92-20802-130-02, p. 4:

1. Turn off the gas to the furnace by “To Turn Off Gas To The Appliance”: shut off the manual gas valve in the gas supply piping outside the furnace casing, set the thermostat to its lowest setting, turn off all electric power to the appliance if service is to be performed, remove the burner access door, turn the gas control knob or switch to OFF and replace the door 92-20802-128-03, p. 4. In that list the power step is conditional, but the manual’s warning is to turn off electrical power to the furnace before removing the front access door 92-20802-128-03, p. 7, and its operating instructions turn off all electric power before the burner access door is removed 92-20802-128-03, p. 4. Full steps: shutting the furnace down.
2. Call your service technician or gas supplier 92-20802-128-03, p. 4.

The manuals do not go further, and they leave routine maintenance to a qualified installer, service agency or the gas supplier 92-20802-128-03, p. 7.

The first cause on the 57 card is blockage or improper termination in the inlet or exhaust vents 92-24161-111-17, p. 93. The owner’s manuals cover the vent only as a warning: if the vent pipe has become disconnected, toxic fumes can escape into the home, so do not operate the furnace, and appropriate service must be applied 92-20802-128-03, p. 8; 92-20802-130-02, p. 8. The carbon monoxide warning on the cover of the installation instructions says to check that the furnace vent and air intake terminals are not obstructed in any way during all seasons 92-24161-111-17, p. 1; 92-24161-144-09, p. 1. The owner’s manuals do not repeat that line.

On condensing furnaces the owner’s manual adds that the furnace has a pressure switch that shuts off the main burners if the condensate drain line becomes blocked, and that the condensate flow can be checked by eye while the furnace runs 92-20802-128-03, p. 8. The 57 card does not list the drain; on the single-stage condensing furnaces a blocked condensate drain is a cause of a different code, 59 92-24161-111-17, p. 93.

When to call a licensed technician

Everything on the card’s solution list is service work 92-24161-111-17, p. 93:

• The vent system: blockage and termination, and vent length and number of elbows checked against the specification sheets and installation instructions, with excess venting removed.
• The inducer, its wiring and electrical connections, and the inducer relay on the control board.
• The pressure switch hoses, which the card lists as disconnected, blocked, split or cut, and the pressure switch itself.
• The high altitude kit: whether the elevation of the installation calls for one under the furnace specifications. The card also lists sporadic wind gusts as a cause and answers them with proper termination and a check of whether a high altitude kit is needed.
• Loose or faulty wiring.

The two-stage and communicating cards give the same nine causes and solutions 92-24161-122-12, p. 96; 92-24161-124-12, p. 118.

Notes for different models

Series	Where	Wording	Source
92P, 92T, 95P, 95T	code list	“PRESS SWITCH STUCK OPEN WHEN SHOULD BE CLOSED”	92-24161-118-16, p. 87; 92-24161-111-17, p. 87
92P, 92T, 95P, 95T, 2017 revisions	fault card	“PRESSURE SWITCH OPEN”	92-24161-111-17, p. 92
801S, 801P, 801T	code list (no fault cards)	“PRESS SWITCH STUCK OPEN WHEN SHOULD BE CLOSED”	92-24161-142-15, p. 39; 92-24161-144-09, p. 39
96P, 96T, 802P	code list	“HIGH PRESSURE SWITCH OPEN”	92-24161-122-12, p. 88; 92-24161-146-05, p. 40
96P, 96T	fault card	“HIGH PRESSURE SWITCH OPEN, INDUCER ON HIGH SPEED”	92-24161-122-12, p. 96; 92-24161-157-04, p. 96
96V, 97V, 802V	fault card	“HIGH PRESSURE SWITCH OPEN, INDUCER ON HIGH SPEED”	92-24161-124-12, p. 118; 92-24161-126-04, p. 101; 92-24161-148-07, p. 71
801T Ultra Low NOx	fault card title, read from the page image	“COMBUSTION PRESSURE SWITCH OPEN WHEN SHOULD BE CLOSED”	92-24161-164-01, p. 38
Fault code label 92-103343-01-00 (listed on the RGGE and RGJF support pages)	label, no models printed	“High Pressure Switch Open”	92-103343-01-00, p. 1
RGPN, RGPS, RGLN, RGLS	blink legend (green LED), 2 blinks	“PS Circuit open”	92-24161-38-12, p. 39

The blink legend is a different board, and no document matches its counts to the two-digit codes. The 801 series manuals have no fault cards for 57: they give the code list, the troubleshooting legend (“Pres. Switch stuck open, should be closed”) and the lockout rules 92-24161-144-09, pp. 39, 40, 50. The 98V card has the same title as the 96V card, but its text could not be extracted, so this page does not paraphrase it 92-24161-159-03, p. 98. The 801T Ultra Low NOx has two more pressure switch codes of its own, 43 and 56, for an ignition pressure switch 92-24161-164-01, pp. 36–37.

On the 96V and 97V diagnostics charts 57 is listed as a warning or a critical fault (fault level 1,2), at priority 17 and 20 (96V-chart; 97V-chart).

For Ruud, the documents show only the replacement-parts line “www.myrheem.com/myruud.com” in the 802P manuals 92-24161-146-05, p. 50; 92-24161-147-04, p. 46 and the model name R801T on both a Ruud and a Rheem specification sheet (G22-556 Rev 8; G11-662 Rev 7); none ties a Ruud furnace to a series on this page.

Related Rheem and Ruud codes

• 45 “Low Pressure Switch Open, Inducer on High Speed”
• 46 “Low Pressure Switch Open, Inducer on Low Speed”
• 55 “PRESSURE SWITCH STUCK CLOSED WHEN SHOULD BE OPEN”

See also

• Heat pump vs gas calculator
• HVAC and furnace tax credits in 2025 and 2026: 25C, 25D, 30C

Other gas furnaces: Carrier, Goodman, Lennox

All Rheem and Ruud codes

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