Bosch Error Code Protection letter + Hz: Limited operation – protection letter before the frequency (Heat Pump)
Bosch error code Protection letter + Hz on a heat pump means: Limited operation - protection letter before the frequency. It is also called Bosch diagnostic code Protection letter + Hz.
Homeowner? What Bosch code Protection letter + Hz means for you
Usually minor Your heat pump is reporting: Limited operation - protection letter before the frequency. This code is usually informational or minor. The safe checks below often clear it; call us if it keeps showing up.
Safe things you can check yourself
- Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
- Check both breakers and the outdoor disconnect box beside the outdoor unit; all should be ON.
- Look at the air filter. If it is grey and clogged, replace it; a blocked filter causes many shutdowns.
- In winter, keep snow and ice off and away from the outdoor unit. A short defrost cycle with steam is normal.
- Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.
Call (647) 657-2977Book a service call
Licensed technicians serving Vaughan, Toronto and the GTA.
What does Bosch error code Protection letter + Hz mean?
If the first character on the board display is a protection letter followed by two digits, the unit keeps running but in a limited condition and the digits are the compressor frequency in Hz. The table lists limits for high pressure, low pressure, oil return, current, T5 discharge temperature, IPM temperature, compressor ratio and low voltage, plus a forced operation mode. The letter-to-meaning column could not be read from the text export, so the individual letters are not recorded here.
Applies to: BOVA IDS Premium Connected (36-60) and IDS Light (BOVA15) heat pumps
Bosch models that use code Protection letter + Hz
BOVA15-24BOVA15-36BOVA15-60BOVA36-20BOVA60-20
Other Bosch Heat Pump codes
All Bosch Heat Pump error codes →
Bosch code Protection letter + Hz: homeowner questions
What does Bosch code Protection letter + Hz mean?
Limited operation - protection letter before the frequency. If the first character on the board display is a protection letter followed by two digits, the unit keeps running but in a limited condition and the digits are the compressor frequency in Hz. The table lists limits for high pressure, low…
Is it safe to keep using my heat pump with code Protection letter + Hz?
Usually yes. Code Protection letter + Hz is normally minor, but if it keeps coming back have it checked.
Can I reset Bosch code Protection letter + Hz myself?
You can try one reset (power off for 30 seconds, then on). If Bosch code Protection letter + Hz comes back, the cause is still there and a licensed technician should check it.
Who can fix Bosch code Protection letter + Hz near me?
Aurora Star Tech Inc. repairs Bosch heat pumps in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.
Homeowner help: AC Running But Not Cooling: What to Check · Heat Pump Not Heating or Blowing Cold Air
Troubleshooting guides
- Force cooling for charging with the FORCE button Bosch · Heat Pump
- Pair the gateway by Bluetooth (Connect button) Bosch · Heat Pump
- Read system values with the CHECK button (point check) Bosch · Heat Pump
- Restart the gateway (Reset button) Bosch · Heat Pump
- Run the gateway diagnostic (Factory + Connect buttons) Bosch · Heat Pump
- Start a manual defrost test (hold FORCE 6 s) Bosch · Heat Pump
Source: Bosch IDS Premium Connected BTC 762003301 D (02.2025), 18.9 System Protection Status Codes p.49 and 18.10 Parameter Point Check Table p.50; IDS Light BTC 762003308 D (01.2025), 17.9 p.43 and 17.10 p.44. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.