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Bosch MED17.1.62 - TC1793

Bosch MED17.1.62 - TC1793 FAQ | bFlash Support

Bosch MED17.1.62 - TC1793

Errors

Quickly identify and resolve common issues encountered while working with the Bosch MED17.1.62 control unit.

71-01-02-03-02 : UDS RX unexpected size

Occurs when the immobilizer is active, blocking OBD programming attempts.

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Files not found

The specific software version for this ECU is missing from the bFlash server.

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[ISOTP API] No data / RX error

The ECU refused programming because safety conditions like voltage were not met.

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Checksum is invalid (0x00000001)

Detected incorrect checksums, often caused by previous tuning tools.

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Concerns vehicles from

Audi Bentley Volkswagen

71-01-02-03-02 : UDS CheckProgrammingPreconditions RX unexpected size

Method: OBD / Recovery: BOOT

Issue: The programming process is blocked because the vehicle's immobilizer system is currently active and protecting the ECU.

Solution
  • Switch the programming method to BOOT mode to bypass the immobilizer restriction.
  • Ensure the ECU is removed from the vehicle and wired according to the bFlash BOOT instructions.
To understand more

For VAG group vehicles (Audi/VW/Bentley), the immobilizer (Immo) must be deactivated for successful OBD writing. When it remains active, the ECU returns an unexpected response size during the pre-programming check, necessitating a direct connection via BOOT mode for recovery or modification.

Files not found

Method: OBD / Recovery: BENCH

Issue: Your specific ECU software version or hardware ID is not yet cataloged on the bFlash cloud servers.

Solution
  • Perform a full BENCH read of the ECU to extract the original data.
  • Send the generated file to support@bflash.eu.
  • Our team will verify the file and add it to the server to enable future OBD operations.
To understand more

Virtual Reading (VR) or server-side support relies on a database of existing files. If a new or rare firmware update is encountered, a physical read via BENCH mode is required to provide bFlash with the data structure necessary to support that specific version.

[ISOTP API] No data to read from isotp stack A... : UDS CheckProgrammingPreconditions RX error

Method: OBD

Issue: The ECU has denied the programming request because the physical or software safety environment of the vehicle is incorrect.

Solution
  • Connect a high-quality battery charger to maintain stable voltage (>13V) throughout the process.
  • Use a diagnostic tool to Clear all DTCs (Diagnostic Trouble Codes) before attempting to write.
  • Physically open the vehicle's hood, as some VAG models require this as a security confirmation for programming.
To understand more

The UDS protocol includes a verification phase where the ECU checks for prerequisites. If it detects low voltage, active fault codes, or a closed hood (which signals a non-service environment), it will abort the isotp stack communication to prevent potential bricking of the unit.

Checksum is invalid. error code : 0x00000001

Method: BENCH

Issue: bFlash has detected that the file currently inside the ECU has corrupted or non-standard checksums.

Solution
  • In most cases with Bosch MEDC17 ECUs, you can safely ignore this warning and proceed with the programming.
  • If the error reappears or blocks the actual writing process, Contact our technical support for assistance.
To understand more

This error often occurs when an ECU was previously tuned using a different flash tool that calculates checksums differently. While bFlash detects this integrity mismatch, the MED17.1.62 architecture typically allows a bFlash write to overwrite these values and correct the file structure.