Suburban error code LOCKOUT
Suburban Nautilus IW60: Module board LOCKOUT - the water heater fails to ignite after three Trial-for-Ignition (TFI) attempts (3 s prepurge, ~7 s TFI each); the module board locks out. Indicated on the On-Demand Control Center (or the Switch-and-Light lockout LED). Reset by cycling power OR turning the hot faucet OFF then back ON to restart the cycle. (Suburban ST-42 / ST-60 show ignition failure as code E1 instead.)
What to check, and in what order, is in the app. The flow Suburban tankless — IW60 / ST-42 / ST-60 error code + symptom diagnostic walks this code step by step with the pass/fail measurements, wiring schematics and procedures that go with it, and it works offline in the bay.
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- Suburban Nautilus IW60 Service & Training ManualSuburban (Airxcel)
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