How House Works

Carrier furnace code 34 (3 short, 4 long): ignition proving failure

By How House Works EditorialBased on Carrier, Bryant and Payne service labels and manualsChecked against sources Updated

Furnace control LED

34

“IGNITION PROVING FAILURE”

Printed on 17 model series · 24 documents

58PAV/58RAV Series 131, 58MCB, 58STA/58STX, PG8MAA/PG8JAA, 58SB0A/58SC0A, 810SA, PG80ESAA, 820SA, 58TP0A, 58TN0A, 880TA, 59SC2D, 59SC5A, 59SP5A, 59SC5B, 59SU5A, 935SA, 59CU5A, PG80ESU, Guide TG-GFC80-02 (models not listed), 59MN7A Series 100, 58MVP/58MVB/58UVB · 58P_R-9SM p. 9; 58MCB-4SM p. 15; 58ST-24SI p. 43; IM-PG8J-17 p. 43; 58SC0A-05SI p. 26; 58SB0A-04SI p. 26; II810SA-05 p. 26; IM-PG80ESA-05 p. 26; IM-PG80ESAA-04 p. 27; II820SA-02 p. 26; 58TP0A-02SI p. 37; 58TN0A-02SI p. 35; II880TA-02 p. 35; 59SC2D-02SI p. 61; 59SC5A-13SI p. 67; 59SP5A-18SI p. 70; 59SC5B-04SI p. 63; 59SU5A-05SI p. 51; II935SA-05 p. 51; 59CU5A-01SI p. 65; GFULN80-G-01TS p. 6; TG-GFC80-02 p. 8; 59MN7A-01T p. 9; 58-06T p. 8

Owner checks, then technician

What it means

Code 34 is three short flashes followed by four long ones. Most labels call it “IGNITION PROVING FAILURE”; the 59SP6A, 59TP6A, 59TP6B, Payne PG96VAT, 59TN6B, Bryant 986TC and 59MN7B labels say “IGNITION PROVING FAULT”. The control tries ignition again, and when the tries run out the code becomes 14, an ignition lockout 59SC5A-13SI, p. 67. If the flame signal is lost during the blower on-delay period, the blower comes on for the selected blower off-delay 59SC5A-13SI, p. 67.

The installation manual for the 59TP6C describes the check: the burner flame must be proved at the flame-proving sensor within two seconds, or the control closes the gas valve and repeats the ignition sequence, for up to three more trials 59TP6C-01SI, p. 71.

Check these first

The owner’s manuals do not name code 34. The label lists a closed manual valve and a gas valve that is turned off among the causes 59SC5A-13SI, p. 67, and the owner’s checklist for a furnace that fails to operate lets you check both:

  1. Write the code down before you turn off the power or remove the blower access door OM9GFRC-02, p. 10. Carrier’s 80% owner’s manual does not mention the LED. How to count the flashes: reading a Carrier code.
  2. Check that the manual shut-off valve in the gas supply pipe leading to the furnace is open OM9GFRC-02, p. 11. In Carrier’s 80% manual, the lever is open when it points the same way as the pipe and closed when it is at a right angle to it 80GSFRN-C-03OM, p. 7.
  3. Check that the control switch on the gas valve is in the ON position. The switch is behind the furnace door: first turn off the electrical power supply to the furnace and install a lockout tag before removing the access doors OM9GFRC-02, pp. 10–11; Carrier’s 80% manual says to turn off the electrical power supply and remove the access door before this check 80GSFRN-C-03OM, p. 7. If you must reset the switch to ON, follow the start-up procedure: set the switch to OFF, wait five minutes and smell for gas, including near the floor, and stop if you smell gas, before you set it to ON OM9GFRC-02, pp. 4–6. The 80% manual adds: if either check shows an interruption in the gas supply, make sure the gas has not been shut off for safety reasons 80GSFRN-C-03OM, p. 7.
  4. Never try to light the burners with a match or other source of flame OM9GFRC-02, p. 4; 80GSFRN-C-03OM, p. 3.
  5. If the code has become 14, follow the lockout instruction: “If lockout occurs, main burners fail to light, or blower does not come on, shut down the furnace and call your dealer for service.” OM9GFRC-02, p. 6. Carrier’s 80% manual gives the same instruction if lockout occurs or the blower does not come on 80GSFRN-C-03OM, p. 5.

When to call a licensed technician

  • The burners still fail to light, or the furnace locks out OM9GFRC-02, p. 6.
  • The rest of the label’s list: oxide buildup on the flame sensor, the flame sense current, control ground continuity, a flame sensor that must not be grounded, the green/yellow wire that must be connected to the furnace sheet metal, a defective hot surface igniter, a defective gas valve, low inlet gas pressure, and inadequate flame carryover or rough ignition 59SC5A-13SI, p. 67.
  • The label pairs the flame sensor item with cleaning it with fine steel wool 59SC5A-13SI, p. 67. The owner’s manual does not give that job to owners: it lets untrained people clean and replace air filters and says all other operations must be performed by trained service personnel OM9GFRC-02, p. 2.

Notes for different models

  • Labels word the retries differently: “three more times” on most, “four ignition trials” on the Bryant 820SA and the 58TP0A, and “ignition four times” on the 59SU5A, Bryant 935SA, 59CU5A and Payne PG80ESU 59SC5A-13SI, p. 67; II820SA-02, p. 26; 58TP0A-02SI, p. 37; 59SU5A-05SI, p. 51; GFULN80-G-01TS, p. 6. The 820SA and 58TP0A lists do not include the hot surface igniter or the green/yellow wire II820SA-02, p. 26; 58TP0A-02SI, p. 37.
  • On 3-digit displays, 34.1 is “Ignition fault - during four consecutive ignition trials.” 59TP6C-01SI, p. 56; IM-PG96VTAB-01, p. 54; 58SP0B-01SI, p. 30; II800SB-01, p. 31; the Bryant 935SB prints the same line with slightly different punctuation II935SB-01, p. 48. The 58SP0B, Bryant 800SB and 935SB add 34.2 and 34.3, flame lost after successful ignition, before or after the heating blower on-delay; the 935SB adds 34.4, flame lost at reduced inducer pressure after an earlier 34.3 58SP0B-01SI, p. 30; II800SB-01, p. 31; II935SB-01, p. 48. The 59TP6C, 59TP7A, Bryant 926TC and Payne PG96VTAB use 34.5 to 34.8 for low-heat and high-heat flame lost before or after the on-delay 59TP6C-01SI, p. 56; IM-PG96VTAB-01, p. 54.
  • The 58SU0A has no code 34. Its 1 amber flash, “Low Flame Sense”, names a poor or no ground and a dirty or corroded sensor as causes 58SU0A-05SI, p. 36.

Related Carrier codes

  • 14 “IGNITION LOCKOUT”
  • 34.1 “Ignition fault - during four consecutive ignition trials.”
  • 1 amber flash “Low Flame Sense”

See also

Other gas furnaces: Goodman, Lennox, Rheem and Ruud

All Carrier codes

Carrier is a trademark of its owner. How House Works is not affiliated with or endorsed by Carrier.

Sources

  1. Carrier Corporation. Owner's Manual, Condensing Gas Furnace. OM9GFRC-02, edition 04/20; replaces OM9GFRC-01. Accessed Oct 17, 2026.
  2. Carrier Corporation. Owner's Manual, Non-Condensing, 80% AFUE Gas Furnace. 80GSFRN-C-03OM, edition 08/22; replaces OM8GFRC-02. Accessed Oct 17, 2026.
  3. Carrier Corporation. 58PAV, 58RAV Induced-Combustion Furnaces, Service and Maintenance Instructions, Sizes 045-155, Series 131. Form 58P,R-9SM (Catalog No. 535-835), edition 9-94; replaces 58P,R-8SM. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  4. Carrier Corporation. 58MCB 4-Way Multipoise Fixed-Capacity Condensing Gas Furnace, Service and Maintenance Instructions, Sizes 040-120, Series 110 & 120. 58MCB-4SM, edition 10/09; replaces 58MCB-3SM. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  5. Carrier Corporation. 58STA/STX Single-Stage Deluxe, Induced-Combustion 4-Way Multipoise Gas Furnace, Series 160. 58ST-24SI, edition 08/13; replaces 58ST-23SI. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  6. Payne Heating & Cooling. PG8MAA/PG8JAA Series G: Single-Stage Deluxe, Induced-Combustion 4-Way Multipoise Gas Furnace. IM-PG8J-17, edition 08/13; replaces IM-PG8J-16. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  7. Carrier Corporation. 58SC0A/58SC1A: 80% AFUE, Single-Stage, Multi-Speed ECM, 4-Way Multipoise, Non-Condensing Gas Furnace. 58SC0A-05SI REV B, edition 09/21; replaces 58SC0A-05SI REV A. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  8. Carrier Corporation. 58SB0A/58SB1A: Single Stage, Multi-Speed ECM, Non-Condensing Gas Furnace, Input Capacities 45,000 thru 155,000 Btuh. 58SB0A-04SI, edition 03/20; replaces 58SB0A-03SI. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  9. Bryant Heating & Cooling Systems. 810SA/811SA: 80% AFUE, Single-Stage, Multi-Speed ECM, 4-Way Multipoise, Non-Condensing Gas Furnace. II810SA-05 REV B, edition 09/21; replaces II810SA-05 REV A. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  10. Payne Heating & Cooling. PG80ESAA/PG80ESLA: 80% AFUE, Single-Stage, Multi-Speed ECM, 4-Way Multipoise, Non-Condensing Gas Furnace. IM-PG80ESA-05 REV B, edition 08/21; replaces IM-PG80ESAA-05 REV A. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  11. Payne Heating & Cooling. PG80ESAA/PG80ESLA: Single Stage, Multi-Speed ECM, Non-Condensing Gas Furnace, Input Capacities 45,000 thru 155,000 Btuh. IM-PG80ESAA-04, edition 03/20; replaces IM-PG80ESAA-03. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  12. Bryant Heating & Cooling Systems. 820SA/821SA: 80% AFUE, Non-Communicating, Single Stage, ECM Motor, Variable Speed, 4-Way Multipoise, Non-Condensing Gas Furnace. II820SA-02 REV A, edition 08/21; replaces II820SA-02. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  13. Carrier Corporation. 58TP0A/58TP1A Variable-Speed, ECM Induced-Combustion, 2-Stage 4-Way Multipoise, Non-Condensing Gas Furnace, Series A. 58TP0A-02SI, edition 07/19; replaces 58TP0A-01SI. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  14. Carrier Corporation. 58TN0A/58TN1A: 80% AFUE, Two-Stage, Variable-Speed 4-Way Multipoise, Non-Condensing Gas Furnace, Series A. 58TN0A-02SI REV A, edition 08/21; replaces 58TN0A-02SI. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  15. Bryant Heating & Cooling Systems. 880TA/881TA: 80% AFUE, Two-Stage, Variable-Speed 4-Way Multipoise, Non-Condensing Gas Furnace, Series A. II880TA-02 REV A, edition 08/21; replaces II880TA-02. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  16. Carrier Corporation. 59SC2D Single Stage, 35-in. (889 mm) Tall 4-Way Multipoise Condensing Gas Furnace. 59SC2D-02SI, edition 11/19; replaces 59SC2D-01BSI. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  17. Carrier Corporation. 59SC5A Single Stage 4-Way Multipoise Condensing Gas Furnace, Series 1 and 2. 59SC5A-13SI, edition 01/19; replaces 59SC5A-12SI. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  18. Carrier Corporation. 59SP5A Single Stage, 4-Way Multipoise Condensing Gas Furnace, Series 1 and 2. 59SP5A-18SI, edition 01/19; replaces 59SP5A-17SI. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  19. Carrier Corporation. 59SC5B: Single-Stage, High Efficiency, 4-Way Multipoise, 35-in. (889 mm), Condensing Gas Furnace. 59SC5B-04SI REV E, edition 06/23; replaces 59SC5B-04SI REV D. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  20. Carrier Corporation. 59SU5A: Up to 95% AFUE, Single-Stage, Upflow/Horizontal, Ultra Low NOx, 35-in. Tall, Condensing Gas Furnace (Minor Series 2). 59SU5A-05SI REV D, edition 06/23; replaces 59SU5A-05SI REV C. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  21. Bryant Heating & Cooling Systems. 935SA: Up to 95% AFUE, Single-Stage, Upflow/Horizontal, Ultra Low NOx, 35-in. Tall, Condensing Gas Furnace (Minor Series B). II935SA-05 REV D, edition 06/23; replaces II935SA-05 REV C. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  22. Carrier Corporation. 59CU5A: Single-Stage, Upflow/Horizontal Communicating, Variable Speed ECM, Ultra Low NOx, 35-in Tall Condensing Gas Furnace. 59CU5A-01SI REV D, edition 06/23; replaces 59CU5A-01SI REV C. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  23. Carrier Corporation. 58SU0A 4-Way Multipoise, Ultra Low NOx 80% AFUE Gas Furnace, Input Capacities 40,000 thru 100,000 Btuh. 58SU0A-05SI, edition 11/19; replaces 58SU0A-04SI. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  24. Payne Heating & Cooling. PG80ESU (Minor Series B&C) Troubleshooting Guide: 80% AFUE, Ultra Low NOx, 4-Way Multipoise Gas Furnace. GFULN80-G-01TS, edition 08/23. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  25. Carrier Corporation. Troubleshooting Guide: Mid-Efficiency Variable-Speed, Two-Stage Induced-Combustion Deluxe, 4-Way Multipoise Gas Furnace. TG-GFC80-02, edition 05/18; replaces TG-GFC80-01. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  26. Carrier Corporation. 59MN7A Series 100 Troubleshooting Guide: Variable Speed, Modulating Electronic Condensing Four-Way Multipoise Gas Furnace. Form 59MN7A-01T, edition 9-11. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 19, 2026.
  27. Carrier Corporation. 58MVP Series 170 & 180, 58MVB, 58UVB Troubleshooting Guide: Variable Speed, Two-Stage Electronic Condensing Gas Furnace. Form 58-06T, edition 6-08; replaces 58MVP-10SM. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 19, 2026.
  28. Carrier Corporation. 59TP6C: Two-Stage, Non-Communicating, Variable 25-Speed, ECM Multipoise, Condensing Gas Furnace with InteliSense. 59TP6C-01SI REV A, edition 06/23; replaces 59TP6C-01SI. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  29. Payne Heating & Cooling. PG96VTAB: Two-Stage, Non-Communicating, Variable 25-Speed, ECM Multipoise, Condensing Gas Furnace. IM-PG96VTAB-01 REV A, edition 06/23; replaces IM-PG96VTAB-01. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  30. Carrier Corporation. 58SP0B/58SP1B: 80% AFUE, Non-Communicating, Single Stage, Variable 25-Speed, ECM Motor, 4-Way Multipoise, Non-Condensing Gas Furnace with InteliSense. 58SP0B-01SI, edition 03/23. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  31. Bryant Heating & Cooling Systems. 800SB/801SB: 80% AFUE, Single Stage, Multi-Speed ECM, 4-Way Multipoise, Non-Condensing Gas Furnace. II800SB-01 REV B, edition 06/23; replaces II800SB-01 REV A. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 17, 2026.
  32. Bryant Heating & Cooling Systems. 935SB: Installation, Start-up, Operating and Service Maintenance Instructions (single-stage ultra low NOx condensing; 3-digit display). II935SB-01 REV C, edition 06/23; replaces II935SB-01 REV B. Manufacturer PDF hosted on shareddocs.com, not on the brand website.. Accessed Oct 19, 2026.