HVAC Cheat Sheethvaccheatsheet.com/charts/furnace-codes/trane-s8x1
Trane / American Standard S8B1 / S8X1 / S8X2 Furnace Codes
Covers the single-stage S8B1 and S8X1 and the two-stage S8X2. American Standard sells matching models; check the label on the unit.
| Code | Meaning | What to check |
|---|---|---|
| E01 | Loss of the IRQ or other internal failures (internal IFC error). | Replace the integrated furnace control if it repeats. |
| E2.1 | Retry exceeded: flame never sensed. One-hour lockout after 3 times. | Gas supply, igniter, gas valve, flame sensor. How to fix → |
| E2.2 | Recycles exceeded: flame sensed then lost. One-hour lockout after 10 times. | Flame sensor, ground, gas pressure, pressure switch dropping out. How to fix → |
| E2.3 | 1st-stage gas valve not energized when it should be, exceeded after 10 times. | Gas valve wiring and the circuit through the limits and pressure switch. How to fix → |
| E3.1 | Shorted pressure switch, 1st stage. | Switch stuck closed or a wiring short. How to fix → |
| E3.2 | Open pressure switch, 1st stage. | Vent blockage, hoses, inducer, switch. How to fix → |
| E3.3 | Shorted pressure switch, 2nd stage (S8X2 only). | Switch stuck closed or a wiring short. How to fix → |
| E3.4 | Open pressure switch, 2nd stage (S8X2 only). | Vent blockage, hoses, inducer, switch. How to fix → |
| E04 | Open limit (main thermal, rollout switch, or reverse airflow switch). | Airflow first; a tripped rollout needs a vent and heat exchanger check before resetting. How to fix → |
| E05 | Flame detected, should not be present. | Gas valve leaking through or a shorted flame sense circuit. How to fix → |
| E6.1 | Voltage reversed polarity. | Hot and neutral reversed. |
| E6.2 | Bad grounding. | Furnace and burner ground. |
| E6.3 | Igniter relay fails, or igniter open. | Check the igniter before the control. How to fix → |
| E7.1 | 1st-stage gas valve (MVL) is energized when it should be off. | Gas valve wiring; control. |
| E08 | Flame current is low, but still strong enough to allow operation. | Clean the flame sensor; check ground and gas pressure. How to fix → |
| E11 | Gas valve circuit: 1st-stage valve not energized when it should be, 1st-stage relay stuck closed, or (S8X2) a 2nd-stage valve or relay fault. | Gas valve wiring and the control's valve relays. |
| E12 | Open fuse. | Short in the 24 V wiring. How to fix → |
How to read the codes
- 'IdL' means idle, no thermostat demand. 'Err' is the active alarm menu and 'L6F' holds the last 6 faults; to clear them, hold the Option button for 5 seconds after entering the L6F menu.
- Codes with a decimal (for example E2.1) are sub-codes of the same fault family: 2.x ignition, 3.x pressure switch, 6.x power and igniter.
- Trane marks pressure switch codes E3.3 and E3.4, and items 3 to 5 under E11, as not applicable to the single-stage S8B1 and S8X1.
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: Trane Installer's Guide, S8B1 / S8X1 / S8X2 gas furnaces, 18-CE16D1-1C-EN (2021), Integrated Furnace Control Display Codes, p. 58. 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)
- Lennox G60UH / G60UHV (SureLight boards 100869 and 100870)
- 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)
- 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)
One field tip a week
A short, practical HVAC tip in your inbox every week: diagnostics, charging, airflow and code changes. Free, unsubscribe anytime.
We'll only use your email for the newsletter. Privacy policy.
HVAC Cheat Sheet · Free PT charts, code lookups and calculators for techs at hvaccheatsheet.com