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9/l/

Blocking fault 9/l/ (2/3/8) - UBA 3 or KIM control unit is defective

Buderus · Logamax plus Boilers

What does 9/l/ mean?

Either the UBA 3 or the KIM control unit within the boiler is defective. This critical internal component failure stops all heating operation. This is a blocking fault, requiring a manual reset.

Common Causes

  • Internal control unit failure (UBA 3 or KIM)
  • Electrical fault within the control unit

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Press the 'Reset' button on the BC10 basic controller.

  2. 2

    Power cycle the boiler by switching it OFF and then ON at the main power switch.

  3. 3

    If the fault persists, contact a qualified service technician for diagnosis and potential replacement of the UBA 3 or KIM unit.

Browse all codes in this manual (43)
Verified technical data. Last updated: April 2026

Related Faults

--/Flashing --/ - Communication fault between UBA 3 and BC10 controller0/y/Locking fault 0/y/ (2/8/5) - Return temperature sensor detected over 203°F (95°C)1/a/Blocking fault 1/a/ (3/1/6) - Flue gas sensor temperature too high
Source: Buderus Logamax plus Boilers
Open Manual (Page 49)Search more codes in this manual