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3/l/

Blocking fault 3/l/ (2/1/4) - Fan tacho signal not present

Buderus · Logamax plus Boilers

What does 3/l/ mean?

The tacho signal from the fan is not detected during the boiler's startup or operation, indicating a fan issue. This prevents both heating and domestic hot water. This is a blocking fault requiring a manual reset.

Common Causes

  • Faulty fan
  • Wiring problem to the fan
  • Fan motor issue

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

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

  2. 2

    Check for any obstructions that might prevent the fan from spinning freely.

  3. 3

    If the fault reoccurs, contact a qualified service technician to inspect the fan.

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 48)Search more codes in this manual