Furnace Error Codes by Brand: Carrier, Goodman, Lennox, Rheem

A furnace error code is the control board telling you which safety check stopped the burner: no flame, a weak flame signal, a pressure switch, an overheating limit, a blown low-voltage fuse. The same number means different things on different brands and boards. “33” is a limit or rollout fault on the Carrier board we read and a rollout fault on Rheem’s, while Goodman shows its overheating limit as “E E 3”. So write down the brand, the code and the model number, then look the code up in your maker’s own list. The lookup above, one of our furnace problem guides, does that from the makers’ documents for the Carrier, Goodman, Lennox and Rheem boards we have read, and says who the maker expects to act. The label inside your furnace door has the final word for your board.

General information, not professional advice. Your system’s maker, your manual and a qualified technician decide what’s safe for your equipment, and local codes decide what needs a permit or a licensed installer. Heat and Air Handbook sells nothing and recommends no contractor, product or brand: brands appear here only because their codes are being explained.

How to read the code without opening anything

On the Carrier board we read, you watch the status light through the blower door, the lower door on an upflow furnace, without taking anything off. If your furnace has no window and the display sits behind a door, read your owner’s manual before removing it: Trane notes that a blower door switch cuts power to the blower and gas valve when the door comes off, so the furnace stops. What you see depends on the board:

• A blinking light. On the Carrier 59SC5 board we read, the amber light is either on steady, flashing rapidly, or flashing a two-digit code: the number of short flashes is the first digit and the number of long flashes the second, so three short and three long is 33 (Carrier 59SC5A-11SI, Edition 10/18, page 75 and Fig. 70). A steady light means the control has power and no code. Rapid flashing with no pause is its own signal: reversed line polarity, or on twinned furnaces the transformer phasing.
• A three-character display. Goodman’s current single-stage 80% board (the GR9S80 and the related Amana-brand models in the same manual) shows faults on a seven-segment display, read left to right, such as “E E 3” (Goodman RS6621301, page 41).
• An E-code. Lennox’s ML180UHVK board shows letters while it runs (H for gas heat, C for cooling, A for fan only, a blinking dot when idle) and an E followed by three digits for a fault, such as E250 (Lennox 508547-01, 12/2025, page 47).
• A two-character display. Rheem’s 96V and 96MDV boards show 0 on standby, h or H for gas heat, c or C for cooling and F for the fan, and a number such as 11 or 33 for a fault. Rheem tells technicians to check which way up the display reads first, because a code can appear upside down (Rheem 92-24161-124-08, page 111).

Write the code down before you switch anything off, along with the brand and model from the rating plate. Some boards also keep a short history of past faults (the Goodman and Lennox boards both do), but getting at it means pressing buttons on the board or, on the Carrier board, briefly disconnecting a limit wire behind the upper door. That’s the technician’s job. The code showing through the window is enough for you.

A worked example: the lookup’s starting choice

General information, not professional advice. Your system’s maker, your manual and a qualified technician decide what’s safe for your equipment, and local codes decide what needs a permit or a licensed installer.

The lookup opens on Carrier’s 59SC5 board with the amber light on steady. Carrier’s guide reads a steady light as a control that has power and no code, and its next question is whether the thermostat is calling (59SC5A-11SI, Fig. 70). So the lookup shows: no fault showing; normal status; your check is the thermostat on heat and above room temperature, with the furnace switch and breaker on, from the list in Carrier’s owner’s manual for its 80% furnaces (80GSFRN-B-03OM, page 7); the document; and the reminder that the label inside your furnace door decides. Pick Rheem and 22 instead and it shows an open main limit, with the filter and grilles as your check, while Carrier’s 22 is flame with the gas valve off and goes straight to a technician: the same number, two different problems.

The same faults, brand by brand

Different numbers, the same handful of checks. This table lines up the boards we read so you can see which family your code belongs to. A dash means that board’s list, as we read it, has no code for that fault.

What stopped it	Carrier (59SC5)	Goodman (GR9S80)	Lennox (ML180)	Rheem (96V)
No flame proved; lockout after retries	34, then 14	E E 0	E270	11, then 10
Weak flame signal	within 34	E E 6	E240	12
Flame lost after lighting	within 34	within E E 0	E273	13
Pressure switch didn’t close or opened	31	E E 2	E223, E227	45, 46, 57
Pressure switch stuck closed	23	E E 1	E224	44, 55
Limit open (overheating)	33, then 13	E E 3	E250, E274	22
Flame rollout switch open	33, then 13	E 1 1	E200	33
Flame with the gas valve meant to be closed	22	E E 4	E241, E275	14
Low-voltage (24 V) fuse open	24	E E 5	–	30
Ignitor fault	–	E E L, E E n	E290	–
Refrigerant leak sensor (A2L coil)	–	E A L	E150	–
Polarity or ground	rapid flash (polarity)	E E A	E111, E112	26

Every code we read, by brand

Open your brand for the full list. Meanings are our paraphrase of each maker’s table, not a copy; follow the link in each caption for the maker’s own words. “Who acts” is our reading of each maker’s document: “owner check” means the maker’s causes or actions for that code include something on the owner’s list in the next section (the filter, the gas valve, or one reset the maker prints); “urgent” marks flame sensed with the gas valve meant to be closed; everything else is the technician’s.

Carrier (59SC5A board, amber light): all 14 codes

Code	What the maker’s document says (paraphrased)	Who acts
LED on steady, no flashing	Control powered, no code; Carrier's guide next checks the thermostat signals	Normal
Rapid flashing with no pause	Line polarity wrong, or on twinned furnaces the 24 V transformer phasing	Technician
11: 1 short, 1 long flash	No previous code stored; stored codes clear after 72 hours	Normal
12: 1 short, 2 long	Blower on after power-up: normal, runs 90 seconds	Normal
13: 1 short, 3 long	Limit circuit lockout (limit or rollout open over 3 minutes); auto-reset after 3 hours; see 33	Owner check, then technician
14: 1 short, 4 long	Ignition lockout: no flame proved in 4 tries; auto-reset after 3 hours; see 34	Owner check, then technician
21: 2 short, 1 long	Gas heating lockout: gas valve relay stuck closed, or gas valve wire miswired or shorted; turn power off and wait 5 minutes to retry	Owner check, then technician
22: 2 short, 2 long	Flame proved while the gas valve is off; inducer runs until cleared; Carrier checks for a stuck-open or leaky gas valve	Technician now (urgent)
23: 2 short, 3 long	Pressure switch did not open: blocked pressure tube or switch stuck closed	Technician
24: 2 short, 4 long	24 V fuse open: a short in the 24 V wiring, thermostat leads included; Carrier says use only a 3-amp fuse	Technician
31: 3 short, 1 long	Low or high pressure switch did not close or reopened: vent sizing, blocked or loose tubing, plugged drain, water in the vent, wind, inducer	Technician
33: 3 short, 3 long	Limit or rollout open; rollout needs a manual reset; causes include a dirty filter, restricted ducts, loose blower wheel, gas input	Owner check, then technician
34: 3 short, 4 long	Ignition proving failure: no flame sensed; 3 more tries before code 14; first checks: gas valve off, manual shut-off, ground wire, flame sensor	Owner check, then technician
45: 4 short, 5 long	Control circuitry lockout; auto-reset after 1 hour; Carrier: reset power to clear, replace the control if it repeats	Owner check, then technician

Goodman and Amana (GR9S80-family display): all 22 codes

Code	What the maker’s document says (paraphrased)	Who acts
E E E	Internal fault or IRQ loss on the control: replace the board	Technician
E E 0	Lockout after 3 ignition retries: gas interruption, ignitor, flame sensor, flue blockage, inducer	Owner check, then technician
E E 1	Pressure switch stuck closed at the start of a heat call	Technician
E E 2	Pressure switch open: blocked, pinched or misconnected hose, flue blockage, weak inducer	Technician
E E 3	Open high limit: blocked filters or ducts, blower speed or failed blower	Owner check, then technician
E E 4	Flame detected when there should be none: short in the flame sense circuit, lingering flame, slow-closing gas valve	Technician now (urgent)
E E 5	Open fuse: short in the low-voltage wiring	Technician
E E 6	Low flame signal: coated sensor, sensor position, gas pressure or combustion air	Technician
E E L	Ignitor relay fault on the control	Technician
E E A	Reversed line polarity or grounding error	Technician
E E b	Internal gas valve error	Technician
E E C	External gas valve error	Technician
E 1 1	Open rollout switch: gas pressure, burner alignment or burner restriction	Technician
E E n	Ignitor open: check ignitor wiring, replace a damaged ignitor	Technician
E E J	Inducer relay error: replace the control board	Technician
E E H	Twin error: wiring, or the control board	Technician
E b L	Low blower (circulator) current: hard lockout; loose wiring or a burnt motor	Technician
E b U	Blower current unexpected (too high during pre-purge): hard lockout	Technician
E A F	Lost communication with the R-32 sensor: furnace in leak-response mode, fan only	Technician
E A L	R-32 leak detected: gas heat off, fan at full airflow until 5 minutes after the sensor stops detecting it	Technician (refrigerant leak)
E A S	R-32 sensor fault: furnace in leak-response mode, fan only	Technician
E A r	A2L relay fault on the control: leak-response mode; Goodman's actions include cycling power	Technician

Lennox (ML180UHVK E-codes): all 36 codes, plus the status letters

Code	What the maker’s document says (paraphrased)	Who acts
E000	No error in memory	Normal
E106	Twin communication fault (power off on one furnace, or 24 V out of phase)	Technician
E110	Line voltage low	Technician
E111	Line voltage polarity reversed	Technician
E112	Ground not detected: system shuts down	Technician
E113	Line voltage high	Technician
E114	Line frequency out of range	Technician
E115	Low 24 V (range 18 to 30 V); control restarts if it recovers	Technician
E117	Poor ground detected (warning only)	Technician
E125	Control failed self-check; Lennox: cycle power on the control, replace it if the problem persists	Owner check, then technician
E150	Refrigerant leak detected at the indoor coil; can't clear while the sensor still reports a leak	Technician (refrigerant leak)
E151	Leak detector sensor 1 fault	Technician
E152	Leak detector sensor 2 fault	Technician
E154	Leak sensor 1 communication lost or wrong DIP switch setting; blower runs at least 5 minutes	Technician
E155	Leak sensor 2 communication lost; blower runs at least 5 minutes	Technician
E160	Leak sensor 1 is the wrong type: replace with a Lennox-approved part	Technician
E161	Leak sensor 2 is the wrong type	Technician
E163	Furnace control board failure	Technician
E164	Low GWP (leak sensor) test mode; clears after 1 minute	Normal
E200	Hard lockout: rollout circuit open or previously open	Technician
E204	Gas valve miswired	Technician
E223	Pressure switch failed open: vent and inducer checks	Technician
E224	Pressure switch failed closed	Technician
E227	Pressure switch open during ignition or run	Technician
E240	Low flame current: Lennox's action is 'Clean or replace sensor' and check the ground	Technician
E241	Flame sensed out of sequence, flame still present: Lennox's action starts 'Shut off gas'	Technician now (urgent)
E250	Limit switch circuit open: firing rate, blockage, airflow; 1-hour soft lockout if not closed in 3 minutes	Owner check, then technician
E270	Soft lockout: too many retries, no flame current (gas flow, ignitor, flame sensor)	Owner check, then technician
E271	Soft lockout: too many retries, last one failed on the pressure switch	Technician
E272	Soft lockout: too many recycles, last one on the pressure switch	Technician
E273	Soft lockout: too many recycles after flame failure (flame sensor, ground)	Technician
E274	Soft lockout (1 hour): limit opened repeatedly or stayed open over 3 minutes	Owner check, then technician
E275	Soft lockout (1 hour): flame sensed out of sequence; Lennox: 'Shut off gas', check for a leaking gas valve	Technician now (urgent)
E290	Ignitor circuit fault: measure and replace the ignitor if out of specification; 1-hour soft lockout	Technician
E292	Indoor blower motor can't start (seized bearing, stuck wheel); 1-hour soft lockout	Technician
E390	Low GWP relay stuck on the control	Technician
H, C, A, d or a blinking dot	Status letters: gas heat, cooling, fan only, dehumidifying; blinking dot = idle	Normal

Rheem (96V and 96MDV dual display): all 26 fault codes, plus the normal codes

Code	What the maker’s document says (paraphrased)	Who acts
0	Standby: no fault and no call from the thermostat	Normal
h, H, c, C, F	Normal: low or high gas heat, low or high cooling, continuous fan (hP, HP, dF, cd and Cd are heat pump, defrost and dehumidifying modes)	Normal
d1	No model data (memory card missing): the furnace will not run	Technician
d4	No valid model data on the memory card; furnace still runs	Technician
d6	Horsepower conflict between motor and memory card; furnace still runs	Technician
10	One-hour lockout, shown in turn with the code that caused it (11, 13, 14, 59, 61 or 93)	Technician
11	Failed ignition; after 4 in a row, one-hour lockout (10). Causes: flame sensor, gas valve off, ignitor, control, flame carryover	Owner check, then technician
12	Low flame sense (non-critical): clean or replace the flame sensor, check ground	Technician
13	Flame lost after it was established; retries follow	Technician
14	Flame present with the gas valve off: Rheem calls it 'extremely critical'	Technician now (urgent)
22	Main limit open: the heat exchanger area got too hot. Causes: no or low airflow, the limit control, wiring, a dead blower, gas input too high; Rheem's checks include the ductwork and filters. Open over 150 seconds, the control treats the blower as dead (61) and locks out for an hour (10)	Owner check, then technician
23	HALC circuit open: on these furnaces there is no HALC control, only a jumper wire on the board's connector, and the code usually means that jumper has lost contact	Technician
26	Line and neutral reversed, or poor ground: the furnace won't run in any mode	Technician
30	Open fuse: a 24 V short to common or ground	Technician
33	Rollout limit open: Rheem says it 'indicates a very serious problem that must be repaired' first	Technician
44	Low pressure switch closed with the inducer off (welded, wiring, or bypassed)	Technician
45	Low pressure switch open, inducer on high	Technician
46	Low pressure switch open, inducer on low	Technician
55	High pressure switch closed with the inducer off	Technician
57	High pressure switch open, inducer on high: vent blockage, length, inducer, hoses, wind	Technician
58	Water sensor circuit open	Technician
59	Water sensed in the collector box: blocked condensate drain or trap, or damaged sensor wiring	Technician
60	Blower fault, blower can still run (non-critical): the blower is at its speed, torque or temperature limit; Rheem’s fix is restricted ductwork or a filter that needs cleaning or replacing	Owner check, then technician
61	Blower fault, motor cannot run: furnace shuts down	Technician
66	Blower cutback: the blower is at its speed limit because airflow is restricted (ductwork, an obstruction, or a filter that needs cleaning or replacing); Rheem calls it an operating indicator, and the furnace keeps running	Owner check, then technician
68	The control can't communicate with the blower motor: the furnace won't run	Technician
93	Internal control fault, or voltage on the main gas valve when there should be none: Rheem calls it severe; the furnace shuts down	Technician
99	Notice: the stored fault codes have been cleared	Normal

Bryant, Payne, Trane and other brands

Bryant and Payne belong to the Carrier family. Bryant’s own site signs off as “A Carrier Company”, and payne.com now says “Payne is now WeatherMaker by Carrier” and keeps Payne owner manuals there. But we have not read a Bryant or Payne code table on a maker site, and boards differ even within one maker, so the lookup doesn’t list them. Read the code with the short-and-long-flash method above, then match it to the label inside your furnace door.

Trane and American Standard. We found Trane’s installer’s guide for the S9V2 furnace on Trane Technologies’ literature site, which shows a seven-segment display and errors that alternate with the mode, but not a full fault list in readable text. So the lookup shows Trane as “not confirmed”. What Trane does print for owners is one lockout step: turn the power “on-off-on-off twice in 30 seconds” (Trane 32-5083-1C-EN, 2024, troubleshooting table). The same guide says a tripped flame rollout control or pressure switch “must be investigated by a qualified service technician”.

Other boards from the four listed makers. Two-stage, variable-speed and communicating furnaces often use different codes from the single-stage boards here, and older boards used flash counts that differ again. Even within one document they can differ: Goodman’s service manual for the GR9S80 family still says the diagnostic light on single-stage 80% models flashes six times for a rollout trip (RS6621301, page 20), while its display table shows E 1 1. If your furnace’s label doesn’t match the lookup, the label wins.

What you can check, where you stop, what the technician does

Every maker we read draws the same line. Carrier’s service section says owners can clean and replace filters and that “all other operations must be performed by trained service personnel” (59SC5A-11SI, page 75). Goodman says that if you service the unit “you assume responsibility for any injury or property damage” (RS6621301, page 1), and Lennox says installation and service must be done by “a licensed professional HVAC installer (or equivalent), service agency or the gas supplier” (508547-01, page 1). Trane warns that “do-it-yourself” repairs on an in-warranty unit may void the warranty.

Our part guides give the makers’ own service steps where we found them, with each maker’s cautions. Goodman, Lennox and Trane tell owners not to service the unit, and Trane says do-it-yourself repairs on an in-warranty unit may void the warranty. If you’re not comfortable, or the code comes back, stop and call a technician. Burner orifices, gas pressure, gas piping and the heat exchanger stay a technician’s work. Some states and cities require a licensed gas fitter or a permit for gas work: Massachusetts, for one, requires a permit before gas fitting work and issues those permits only to licensed individuals, apart from gas company employees (248 CMR 3.05). Elsewhere, ask your building department. If the furnace still won’t heat and there’s no code, our checklist for a furnace that won’t turn on goes through it in order.

Newer furnaces: refrigerant leak codes

Newer air conditioners built for the 2025 refrigerant rules may use R-454B or R-32, which EPA lists in safety class A2L (EPA SNAP). EPA’s list marks them “Acceptable with Use Conditions” for this use. Furnaces paired with them read a leak sensor at the indoor coil, and the furnace board acts on it.

• Goodman “E A L” means the R-32 sensor found a leak. The furnace shuts down gas heat, switches on any alarm or ventilation output, and runs the blower at maximum airflow; once the sensor stops detecting refrigerant, the fan runs 5 more minutes before the furnace goes back to normal (RS6621301, page 9).
• Lennox E150 means a refrigerant leak was detected at or in the indoor coil. The code can’t be cleared while the sensor still reports a leak. Lennox’s own test sequence shows the blower powering up and the burners and outdoor compressor shutting down (508547-01, pages 36 and 48).
• Sensor faults (Goodman E A F, E A S, E A r; Lennox E151 to E161, E390) mean the sensor, its wiring or the relay that acts on it has a problem, not necessarily a leak. On Goodman’s board they also put the furnace in fan-only leak mode.

A fan that won’t stop and a cold house can be the furnace doing its job here. Let it run, and don’t unplug or disable the sensor: Lennox’s manual says “Disabling the refrigerant detection functionality on A2L system is prohibited by safety codes”. Finding and fixing the leak means opening the refrigerant circuit, which federal law reserves for EPA-certified technicians, with no homeowner exemption (40 CFR 82.152 and 82.161). Our guide to R-454B and R-32 explains the new refrigerants.

What to write down before you call

• The code exactly as shown: flash counts, or every character on the display, and whether it alternates with another code (Rheem’s one-hour lockout “10” alternates with the code that caused it).
• The brand, model and serial number from the rating plate. Carrier’s owner’s manual says knowing the exact furnace may let the dealer offer suggestions over the phone or prepare for the visit.
• What happened: when it stopped, whether it tried to light, any noise or smell, a power cut, snow or ice on the vent pipes outside, a recent filter change.
• Whether you reset it, and what happened after.
• On a 2025 or newer AC: whether the code is a refrigerant sensor code, and which refrigerant is on the outdoor unit’s label.

Questions worth asking: which part failed and what the code pointed to; whether the part is under warranty (Lennox ties its warranty to the yearly check by a licensed technician, 508547-01, page 41); and on a refrigerant code, whether the leak is being found and repaired or the system is only being topped up. Facing a big repair on an older furnace? Our repair-or-replace check sets your own repair quote against your own replacement quote.

Why code lists online may not match your furnace

Most code pages that rank today are parts sellers, contractors and copy sites. They mix boards and rarely say which document a code came from. A few things you may read elsewhere, checked against the makers’ text:

• “Stored codes clear after 48 hours.” Not on the Carrier board we read: its guide says stored codes are erased after 72 hours, and its installation section says a power cut doesn’t erase them.
• One code list for “Carrier, Bryant and Payne”. Carrier’s own document covers one board family, and codes vary between boards. We found no Bryant or Payne code table on a maker site to confirm the lists match, so the label in your door is the check. Across brands the numbers clash outright: 33 is limit or rollout on the Carrier board and rollout on Rheem’s, and 22 is flame with the gas valve off on the Carrier board but an open main limit on Rheem’s.
• “A flame code means a dirty flame sensor.” Cleaning the sensor is one of the actions, but the makers’ lists also name the sensor’s position or wiring, the ground, gas pressure or the control board, and Carrier’s chart only gets to cleaning after checking the gas valve and the ground wire.
• “Just reset the rollout switch.” Makers disagree: the ones that print an owner reset allow one, and we’d have the cause investigated before any reset. See the stop list above.

What to do now: read the code through the window, write it down with the model number, look it up above, make the owner checks the maker prints, and if it comes back, call. If you smell gas or a CO alarm sounds, leave first and call from outside.

Sources checked on 10 November 2026: Carrier 59SC5A-11SI (Edition 10/18) and 80GSFRN-B-03OM (Edition 08/22) on Carrier’s literature host; Goodman RS6621301 (November 2023) on goodmanmfg.com; Lennox 508547-01 (12/2025) on lennox.com; Rheem 92-24161-124-08 (printed 05/16) on pts.rheem.com; bryant.com and payne.com; Trane 32-5083-1C-EN (2024) and 18-CE03D1-1F-EN (13 May 2020); PHMSA, CPSC, CDC, EPA, the eCFR and 248 CMR 3.05. We could not read a Trane fault list in text, or a Bryant or Payne code table on a maker site.