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Error code reference

Thermador Range Error Code F155

Checksum match error / Cook profile corrupted in EEPROM

Thermador codesThermador range codes

Checksum match error / Cook profile corrupted in EEPROM. Wrong EEPROM data on Display Board.

First step from the service manual

Press Cancel key to reset alarm. If displayed again when starting cooking mode, re-write default data to Display Board EEPROM via P7. If not possible, replace Display Board.

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

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What F155 means on a Thermador range

The F155 error code on a Thermador range indicates a checksum match failure or corrupted cook profile data stored in the EEPROM (Electrically Erasable Programmable Read-Only Memory) on the Display Board. The EEPROM is a small non-volatile memory chip that retains configuration data, cook profiles, and calibration settings even when the range is powered off. When the control system reads this data and the checksum does not match the expected value, it means the stored data has become corrupted or invalid, and the range will not allow a cooking mode to proceed.

This type of error is specific to the Display Board, which contains its own dedicated EEPROM. The board continuously verifies stored data integrity using checksum validation. If the value calculated from the stored data does not match the expected checksum, the F155 fault is triggered. This can happen at startup, when entering a cooking mode, or after a power event that interrupted a write cycle to memory.

Common triggers include power surges or sudden power loss during an EEPROM write operation, which can leave data in a partially written or invalid state. In some cases, the EEPROM chip itself may have reached the end of its write cycle lifespan or suffered a hardware failure. The primary resolution path involves pressing Cancel to clear the alarm, then using the P7 diagnostic procedure to re-write default data to the Display Board EEPROM. If the EEPROM cannot be restored through that process, the Display Board itself must be replaced.

Source: manufacturer service documentation.

Common causes of F155

  1. 01

    Power surge or sudden power loss

    Wiring / connection

    A voltage spike or abrupt power interruption during a memory write cycle can corrupt EEPROM data on the Display Board. This is the most frequent trigger for checksum failures and may be resolved by re-writing default data via the P7 procedure.

  2. 02

    EEPROM data degradation over time

    Part replacement

    EEPROM chips have a finite number of read/write cycles. Over years of use, the memory cells can degrade and fail to retain accurate data, resulting in persistent checksum errors that cannot be corrected by re-writing defaults.

  3. 03

    Failed EEPROM chip on the Display Board

    Part replacement

    The EEPROM chip itself may have suffered a hardware failure, making it impossible to restore valid data through the P7 re-write process. If the re-write procedure fails to clear the F155 error, a faulty chip is likely the cause.

  4. 04

    Display Board failure

    Part replacement

    If the Display Board has experienced broader component failure beyond just the EEPROM, re-writing default data will not resolve the error. Replacement of the entire Display Board is required in this scenario.

  5. 05

    Intermittent electrical connection to the Display Board

    Wiring / connection

    Loose or corroded wiring connections to the Display Board can cause erratic read/write operations to the EEPROM, potentially leading to data corruption. Inspecting connector integrity at the board is a reasonable preliminary step.

See the test procedure for each cause

Frequently asked questions about F155

What does F155 mean on a Thermador range?
F155 indicates a checksum match error, meaning the cook profile or configuration data stored in the EEPROM memory on the Display Board has become corrupted or does not match its expected value. The range detects this mismatch during operation and blocks cooking modes from starting. The error points specifically to the Display Board and its onboard EEPROM, not to the oven sensors or heating components.
Will pressing Cancel clear the F155 error on my Thermador range?
Pressing the Cancel key is the first recommended step and may temporarily clear the alarm. However, if the F155 code returns when you attempt to start a cooking mode, the underlying EEPROM data corruption has not been resolved. In that case, a technician will need to re-write the default data to the Display Board EEPROM using the P7 diagnostic procedure, or replace the Display Board entirely.
Is it safe to use my Thermador range while the F155 error is displayed?
The F155 error is a data integrity fault rather than a safety-critical failure such as a temperature runaway or gas leak. However, the range will typically prevent cooking modes from operating when this fault is active. Attempting to bypass or ignore the error is not recommended, as the corrupted data could affect how the control system manages cooking functions.
How much does it cost to fix a Thermador F155 error?
If the error is resolved by re-writing default data to the EEPROM using the P7 procedure, the cost is primarily a service call fee, which typically ranges from $80 to $150 depending on your location. If the Display Board requires replacement, parts and labor combined can range from $250 to $600 or more, depending on the specific model and board availability. Getting a diagnostic quote before authorizing repairs is advisable.
Can I fix the F155 error on my Thermador range myself?
The initial Cancel key reset is something any user can attempt. However, the next step, re-writing default data to the Display Board EEPROM via the P7 diagnostic procedure, requires access to the service diagnostic mode and familiarity with the control system. If that step is needed, or if the Display Board requires replacement, the repair is best handled by a qualified appliance technician with experience on Thermador equipment.

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