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1051

Alarm 1051 — No communication with external room temp. sensor module (Heating Circ. 1)

Bosch · Alarm List A/W Split (8754) 2018 01 10

What does 1051 mean?

The system is configured to use an external room temperature sensor for heating circuit 1, but communication with the module has not been established. This may be due to an incorrect software setting.

Common Causes

  • Incorrect setting in software for external room temp. sensor
  • External room temperature sensor module not detected

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Access the Service menu.

  2. 2

    Navigate to Set heating/cooling > Heating circ. 1.

  3. 3

    Ensure 'Ext. room temp. sensor' is set to 'No'.

  4. 4

    Verify 'Programming unit' is set to 'RC100/CR10'.

  5. 5

    Consult the room sensors' installer guide for further information.

  6. 6

    Contact a qualified technician if the issue persists.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

1001 / A21/A22/A23/A24Alarm A21/A22/A23/A24 — No communication between system controller and remote control1010 / A11Alarm A11 — No communication via EMS BUS connection1037Alarm 1037 — Outdoor temperature sensor faulty, heating standby mode active
Source: Alarm List A/W Split (8754) 2018 01 10
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