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Bosch · Heat pump

P4 High compressor discharge temperature

High severity Bosch IDS LightBosch IDS Premium Connected

What the control is telling you

Discharge temperature (T5) is too high.

Applies to: Bosch IDS Light BOVA15-24/36/60 and IDS Premium Connected BOVA36-20/60-20 R-454B heat pump outdoor units

Likely causes

  • Closed valves or restricted lines
  • Low charge
  • Poor airflow
  • Sensor fault

Test and repair steps

  1. Open service valves and check the lines.
  2. Check refrigerant charge and airflow.
  3. Check T5 resistance.

Models that show this code

5 models in Bosch IDS Light, Bosch IDS Premium Connected

BOVA15-24BOVA15-36BOVA15-60BOVA36-20BOVA60-20

Other codes on the same units

  • n00-nCF Outdoor fan motor driver fault
  • o37 Low refrigerant in heating
  • P0 Control board / compressor IPM overheating
  • P1 High pressure protection
  • P5 Condenser coil temperature protection (cooling)
  • P11 High pressure protection (transducer)
  • P21 Low pressure protection
  • P31 Input over-current protection

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Source: Bosch IDS Light installation BTC 762003308 D (02.2025), Fault Code Table 23 and 17.12 Error Code Troubleshooting, p.42-59; Bosch IDS Premium Connected installation BTC 762003301 D (02.2025), Fault Code Table 22 and 18.12 Error Code Troubleshooting. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.