Checksum Error

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Q: I have wrote the Mod file onto the vehicle but it does not start, or non starter no MIL light and P0605 ROM error?

A: Before flashing the ECU, You should check to see if your flash tool supports check-sum correction for the protocol you are using.

  • If your tool cannot compute the check-sum then you must raise a support ticket and we will correct it.

A: Your new tuned file has already been modified and has had a 3rd party check-sum installed that the tool cannot correct. PCW can fix this for you please raise a ticket and request a check-sum repair

  • TUNED FILES FROM THE PCW SERVER ARE NOT CORRECTED UNLESS STATED ON THE FILE SUMMARY WINDOW, BEFORE DOWNLOADING THE FILE


Check-sum or Hash-sum Explained

A check-sum or hash sum is a small-size datum from a block of digital data for the purpose of detecting errors which may have been introduced during its transmission or storage. It is usually applied to an installation file after it is received from the download server. By themselves check-sums are often used to verify data integrity, but should not be relied upon to also verify data authenticity.

The actual procedure which yields the check-sum, given a data input is called a check-sum function or check-sum algorithm. Depending on its design goals, a good check-sum algorithm will usually output a significantly different value, even for small changes made to the input. This is especially true of cryptographic hash functions, which may be used to detect many data corruption errors and verify overall data integrity; if the computed check-sum for the current data input matches the stored value of a previously computed check-sum, there is a very high probability the data has not been accidentally altered or corrupted.

Check-sum functions are related to hash functions, fingerprints, randomization functions, and cryptographic hash functions. However, each of those concepts has different applications and therefore different design goals. Check-sums are used as cryptographic primitives in larger authentication algorithms. For cryptographic systems with these two specific design goals, see HMAC.

Check digits and parity bits are special cases of check-sums, appropriate for small blocks of data (such as Social Security numbers, bank account numbers, computer words, single bytes, etc.). Some error-correcting codes are based on special check-sums which not only detect common errors but also allow the original data to be recovered in certain cases.