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5428

Alarm Heat Pump Z1 suction gas sensor TR5 faulty

Bosch · Heat Pumps

What does 5428 mean?

This alarm indicates a fault with the suction gas sensor TR5 for Heat Pump Z1. This could be due to a sensor failure or a short circuit in the cable. It triggers after 3 faults in 2 hours, or 15 minutes of continuous failure or short circuit.

Common Causes

  • sensor TR5 or its signal cable failure.
  • Screw terminal on the I/O board to sensor TR5 not tightened.
  • sensor TR5 or its signal cable short circuited.
  • Defective I/O board.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Locate the I/O board and check the screw terminal connection for sensor TR5 to ensure it is tightened.

  2. 2

    If the alarm persists, contact a qualified technician to check the sensor and its cabling.

  3. 3

    Contact customer support if the issue continues.

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

Related Faults

5203Alarm Outdoor sensor TL1 faulty5206Alarm Flow sensor T0 faulty5209Alarm Z1 heat transfer fluid out sensor TC1 faulty
Source: Bosch Heat Pumps
Open Manual (Page 8)Search more codes in this manual