Editorial & technical review
- Written by ApplianceWorth Editorial Team
- Technically reviewed by Victor — appliance technician
- Last reviewed 2026-07-01
- Applies to Bosch refrigerators
- Confidence medium
- Also displayed as FD, ID, R1, RD, RT, U1
- Sources Manufacturer service documentation and field-repair experience · Methodology · Report a correction
What this code means
The control is receiving an invalid signal from a temperature or defrost sensor circuit. The exact sensor depends on the displayed code.
Most likely causes
- A failed temperature sensor
- A loose or damaged connector
- A broken sensor harness
- A main-control input fault
Safe checks for the owner
- Confirm both compartments are maintaining safe temperatures.
- Disconnect power for five minutes and retry once.
- Do not remove evaporator covers or test live circuits unless qualified.
Estimated U.S. repair cost
$220–$500, depending on model, access, parts availability and local labor.