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Error code reference

Bosch Refrigerator Error Code C1

Cycle abnormal or defective

Bosch codesBosch refrigerator codes

Cycle abnormal or defective — compressor works for over 3 hours when FD-S or RD-S temperature is over 23°F.

First step from the service manual

Check for refrigerant leakage.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What C1 means on a Bosch refrigerator

The C1 error code on a Bosch refrigerator indicates an abnormal compressor cycle condition. Specifically, the compressor has been running continuously for more than 3 hours while the freezer door sensor (FD-S) or refrigerator door sensor (RD-S) temperature remains above 23 degrees Fahrenheit. Under normal operation, the compressor runs in cycles, pulling temperatures down to setpoint and then shutting off. When the compressor cannot achieve the target temperature within a reasonable runtime, the control board logs the C1 fault to alert the technician that the refrigeration system is failing to maintain proper cooling.

The most critical first diagnostic step is checking for refrigerant leakage. A low refrigerant charge is the most common reason a compressor will run indefinitely without achieving target temperatures. Without adequate refrigerant, the system cannot transfer heat effectively, and the compressor simply keeps running in a futile attempt to cool the cabinet. Beyond refrigerant loss, a failed or weakened compressor, a blocked or dirty condenser, a faulty condenser fan motor, or a restriction in the sealed system can all produce the same symptom: extended compressor runtime with insufficient cooling.

Because the fault condition is tied directly to temperature sensor readings from FD-S and RD-S, a failed temperature sensor reporting an artificially high temperature could also trigger C1 even if the refrigeration system itself is functioning correctly. Technicians should verify sensor readings are accurate before condemning sealed system components. Sealed system repairs including refrigerant recharge require EPA Section 608 certification and specialized equipment.

Source: manufacturer service documentation.

Common causes of C1

  1. 01

    Refrigerant Leak

    Part replacement

    A leak in the sealed refrigeration system reduces the refrigerant charge, preventing the compressor from achieving target temperatures no matter how long it runs. Look for oily residue around refrigerant line connections or use a leak detector to confirm.

  2. 02

    Dirty or Blocked Condenser Coils

    Wiring / connection

    Heavy dust and debris buildup on the condenser coils reduces heat dissipation, forcing the compressor to run longer without reaching setpoint. Inspect the condenser coils and clean them if they are coated with lint or debris.

  3. 03

    Condenser Fan Motor Failure

    Part replacement

    If the condenser fan motor is not running, heat cannot be expelled from the refrigeration system efficiently, causing the compressor to run continuously. Check that the condenser fan spins freely and verify the motor receives proper voltage.

  4. 04

    Faulty Temperature Sensor (FD-S or RD-S)

    Part replacement

    A defective freezer door sensor or refrigerator door sensor can report an inaccurately high temperature, triggering the C1 fault even when the compressor and sealed system are working correctly. Check sensor resistance values against specification and replace if out of range.

  5. 05

    Weak or Failed Compressor

    Part replacement

    A compressor that has lost pumping efficiency will run for extended periods without building adequate pressure to cool the cabinet. This is typically diagnosed by checking running amperage and refrigerant system pressures.

See the test procedure for each cause

Frequently asked questions about C1

What does C1 mean on a Bosch refrigerator?
The C1 code means the compressor has been running for more than 3 hours continuously while the freezer door sensor or refrigerator door sensor temperature remains above 23 degrees Fahrenheit. This tells the control board that the refrigeration system cannot reach its target temperature within a normal cycle. The most common cause is a refrigerant leak, but condenser issues and failed sensors can also trigger this code.
Can I fix a C1 error on my Bosch refrigerator myself?
Some causes, such as cleaning dirty condenser coils or confirming the condenser fan is running, can be checked by a knowledgeable DIYer. However, if the root cause is a refrigerant leak, a sealed system restriction, or a failed compressor, the repair requires EPA Section 608 certified technicians and specialized equipment. Attempting to add refrigerant without proper certification and tools is not recommended.
Is a C1 error on a Bosch refrigerator a safety concern?
The C1 fault itself is not an immediate safety hazard, but it does mean your refrigerator is not maintaining safe food storage temperatures. Food stored in a refrigerator running a C1 error may reach temperatures that promote bacterial growth. Address the fault promptly and check internal temperatures with a thermometer to determine if food is still safe.
How much does it cost to repair a Bosch refrigerator showing a C1 error?
Repair costs vary significantly depending on the root cause. Cleaning condenser coils is inexpensive, typically in the range of $50 to $150 for a service call. A refrigerant recharge or leak repair can range from $200 to $600 or more. Compressor replacement is the most expensive repair, often ranging from $400 to $900 or higher depending on labor and parts availability.
Will resetting my Bosch refrigerator clear the C1 error code?
Resetting the refrigerator may temporarily clear the C1 code from the display, but the fault will return if the underlying problem is not corrected. Because the code triggers only after the compressor has run for over 3 hours without achieving temperature, it represents a real system condition rather than a transient glitch. A proper diagnosis and repair of the root cause is necessary to permanently resolve the code.

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