American Standard S9V2 E2.1 ignition retry lockout

What Does Error E2.1 Mean?

On the documented American Standard S9V2, E2.1 means ignition retries were exceeded because flame was never sensed, followed by a one-hour lockout after three attempts. The code reports the failed ignition outcome; it does not prove whether gas delivery, ignition, grounding, flame sensing, venting, or control caused it. Applies to: S9V2 S-Series two-stage condensing gas furnaces This definition is restricted to S9V2 S-Series furnaces using the seven-segment integrated control display in the cited installer guide. Do not translate an older blink count or another American Standard furnace code as E2.1. Owner-safe checks: From outside closed panels, save E2.1, confirm the thermostat demand, and note sounds or factory-port observations without initiating more ignition attempts. Qualified technician: Gas pressure, venting, safeties, igniter, valve, burner, grounding, flame-current, and live control tests require licensed furnace service.