Suburban ST42A / ST60A error code EC
Communication Failure (LOCKED) - the line controller (User Control Panel) has lost communication with the Module Board; the UCP will only display EC. Verify the ribbon/harness between the User Control Panel and the Module Board is seated and undamaged; if it still fails, replace the Module Board.
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 ST-42/ST-60 Service Manual (Error Codes)Suburban (Airxcel)
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