# Trane S8B1 gas furnaces error codes | Costolio URL: https://costolio.com/home/appliances/trane/trane-s8b1-gas-furnaces/ Updated: 2026-11-02 # Trane S8B1 gas furnaces error codes 11 furnace error codes for Trane S8B1 gas furnaces, what each one means and what to try, paraphrased from Trane's own source. Codes vary by model, so confirm in your own manual. Safety. The manual warns: if you smell gas, do not touch switches or light anything, leave and call your gas supplier. Repairs are for a qualified installer or service agency. Source: [Installer's Guide 18-CE09D1-1E-EN, S8B1 gas furnace (Trane)](https://elibrary.tranetechnologies.com/public/residential-hvac/Literature/Installation/18-CE09D1-1E-EN_05062020.pdf). ## All codes - [E2.1](https://costolio.com#e2-1) Retry exceeded: flame never sensed; one hour lockout after 3 times. - [E2.2](https://costolio.com#e2-2) Recycles exceeded: flame sensed then lost; one-hour lockout after 10 times. - [E3.1](https://costolio.com#e3-1) Pressure switch is shorted. - [E3.2](https://costolio.com#e3-2) Pressure switch is open. - [E04](https://costolio.com#e04) Open limit (main limit, rollout or reverse airflow switch). - [E05](https://costolio.com#e05) Flame detected when it should not be. - [E6.1](https://costolio.com#e6-1) Voltage reversed polarity. - [E6.2](https://costolio.com#e6-2) Bad grounding. - [E6.3](https://costolio.com#e6-3) Igniter open. - [E08](https://costolio.com#e08) Flame current is low but still enough to run. - [E12](https://costolio.com#e12) Open fuse. ## E2.1 What it means: Retry exceeded: flame never sensed; one hour lockout after 3 times. This one often needs a licensed technician. ### What to try - Have a qualified technician check it. ## E2.2 What it means: Recycles exceeded: flame sensed then lost; one-hour lockout after 10 times. This one often needs a licensed technician. ### What to try - Have a qualified technician check it. ## E3.1 What it means: Pressure switch is shorted. This one often needs a licensed technician. ### What to try - Have a technician check the pressure switch. ## E3.2 What it means: Pressure switch is open. This one often needs a licensed technician. ### What to try - Have a technician check the pressure switch. ## E04 What it means: Open limit (main limit, rollout or reverse airflow switch). This one often needs a licensed technician. ### What to try - Have a qualified technician check why the limit opened. ## E05 What it means: Flame detected when it should not be. This one often needs a licensed technician. ### What to try - Have a qualified technician check it. ## E6.1 What it means: Voltage reversed polarity. This one often needs a licensed technician. ### What to try - Have a qualified technician check the polarity. ## E6.2 What it means: Bad grounding. This one often needs a licensed technician. ### What to try - Have a qualified technician check the grounding. ## E6.3 What it means: Igniter open. This one often needs a licensed technician. ### What to try - Have a qualified technician check the igniter. ## E08 What it means: Flame current is low but still enough to run. This one often needs a licensed technician. ### What to try - Have a technician check the flame current. ## E12 What it means: Open fuse. This one often needs a licensed technician. ### What to try - Have a technician check the fuse. ### Source - [Installer's Guide 18-CE09D1-1E-EN, S8B1 gas furnace (Trane)](https://elibrary.tranetechnologies.com/public/residential-hvac/Literature/Installation/18-CE09D1-1E-EN_05062020.pdf) (checked 2026-11-02) Brand names and model names are trademarks of their owners. Costolio is not affiliated with or endorsed by any manufacturer. ## Related - [Carrier 58MVP, 58MVB, 58UVB variable-speed condensing gas furnaces error codes](https://costolio.com/home/appliances/carrier/carrier-58mvp-58mvb-58uvb-variable-speed-condensing-gas-furnaces/) - [Lennox SLP99DFV gas furnaces error codes](https://costolio.com/home/appliances/lennox/lennox-slp99dfv-gas-furnaces/) - [Goodman MVS80 / CVS80 ultra-low NOx furnaces error codes](https://costolio.com/home/appliances/goodman/goodman-mvs80-cvs80-ultra-low-nox-furnaces/) - [All appliance error codes](https://costolio.com/home/appliances/)