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Lennox G60UH / G60UHV Furnace Codes
Boards 18M3401, 46M9901, 18M9901 and 49M5901 use two LEDs (DS1 and DS2) instead; see the other SureLight table.
| Code | Meaning | What to check |
|---|---|---|
| Pulse | Power on, standby. | |
| Heartbeat | Normal operation: heating demand at the thermostat. | |
| 1 + 2 | Low flame current in run mode. | How to fix → |
| 1 + 3 | Flame sensed out of sequence; flame still present. | Gas valve leaking through or a shorted flame sense circuit. How to fix → |
| 2 + 3 | Low pressure switch failed open. | How to fix → |
| 2 + 4 | Low pressure switch failed closed. | How to fix → |
| 2 + 5 | High pressure switch failed open. | How to fix → |
| 2 + 6 | High pressure switch failed closed. | How to fix → |
| 2 + 7 | Low pressure switch opened during the ignition trial or heating demand. | How to fix → |
| 3 + 1 | Limit switch open. | How to fix → |
| 4 + 1 | Watchguard: maximum retries exceeded. | How to fix → |
| 4 + 2 | Watchguard: maximum retries exceeded, or the last retry was caused by the pressure switch opening. | How to fix → |
| 4 + 3 | Watchguard: maximum retries exceeded, or the last retry was caused by flame failure. | How to fix → |
| 4 + 5 | Watchguard: limit open longer than 3 minutes. | How to fix → |
| 4 + 6 | Watchguard: flame sensed out of sequence; flame signal gone. | How to fix → |
| 4 + 7 | Ignitor circuit fault: failed ignitor or triggering circuitry. | How to fix → |
| 4 + 8 | Low line voltage. | |
| 5 + 1 | Hard lockout: rollout circuit open or previously opened. | Find why the flame rolled out before resetting. How to fix → |
| 5 + 2 | Control failed its self check (internal error). Restarts if the error clears. | |
| 5 + 3 | No earth ground. Restarts if the error clears. | |
| 5 + 4 | Reversed line voltage polarity. Restarts if the error clears. | Swap line and neutral. |
| 5 + 6 | Low secondary (24 VAC) voltage. | How to fix → |
How to read the codes
- The LED flashes X times, pauses, then flashes Y times. For example 2 flashes, a pause, then 3 flashes is code 2 + 3.
- A slow pulse is standby; a heartbeat pattern is normal heating.
Codes point to a circuit, not a part. Test before replacing anything, and never jumper a limit, rollout or pressure switch to keep a furnace running. Gas and line-voltage work is for trained technicians.
Source: Lennox SureLight Ignition System, Two Stage and Two Stage Variable Speed, Service Literature Corp. 0222-L7 (revised 11-2006), Table 7. The "meaning" column follows the manufacturer's wording; "what to check" is our field summary. Always go by the label on the furnace you're working on.
Related
- How to read furnace LED flash codes
- Furnace pressure switch troubleshooting
- Flame sensor microamps and cleaning
Other brands
- Lennox Merit ML180UH (80% single-stage)
- Carrier 58CVA / 58CVX (80% variable-speed two-stage)
- Rheem / Ruud R96V / 96MDV (96% two-stage communicating)
- Goodman / Amana GR9S80 / GD9S80 (80% single-stage)
- Trane / American Standard S9X1 / S9X2 / S9B1 (96% condensing)
- Lennox SL280UHV (80% two-stage variable speed)
- Goodman / Amana / Daikin GM9S96 / GC9S96 / GM9S92 (96% and 92% condensing, single-stage)
- Carrier 59TP6C two-stage condensing with InteliSense (Performance series)
- Lennox G60DF / G60DFV (older two-stage SureLight boards 18M3401, 46M9901, 18M9901, 49M5901)
- Rheem / Ruud R801T Ultra Low NOx (14 ng/J) single-stage upflow/horizontal, constant-torque blower
- Rheem / Ruud 802V / 80MDV (80% two-stage communicating, ECM blower; model numbers (-)802V and (-)(-)80MDV)
- Trane / American Standard S8B1 / S8X1 / S8X2 (80% single-stage and two-stage)
- Goodman / Amana GMVC96 / GCVC96 (96% two-stage variable-speed, *MVC96*BA and *CVC96*BA)
- Goodman / Amana GMVS96 / AMVS96 U-revision (96% variable-speed with analog pressure sensor, model numbers GMVS96*U and AMVS96*U)
- Goodman / Amana GMVM96 / GCVM96 / AMVM96 / ACVM96 (96% modulating, model numbers *MVM96 and *CVM96)
- Rheem / Ruud R801T / 80MSX (80% single-stage, constant-torque blower; model numbers (-)801T and (-)(-)80MSX)
- Rheem / Ruud 802P / 80MDP (80% two-stage, model numbers (-)802P and (-)(-)80MDP)
- Rheem / Ruud 802T / 80MDT (80% two-stage with constant-torque blower, model numbers (-)802T and (-)(-)80MDT)
- Rheem / Ruud 801S / 801P / 80MSS / 80MSP (80% single-stage, model numbers (-)801S, (-)801P, (-)(-)80MSS and (-)(-)80MSP)
- Carrier 58STA / 58STX (80% single-stage, 4-way multipoise)
- Carrier 58SB0A / 58SB1A (single-stage, non-condensing)
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