Cummins .XCAL Checksum Correction

Cummins .XCAL checksum correction

A Cummins .xcal calibration carries its own verification values. Change a table in Calterm, in WinOLS or in a hex editor and those values no longer describe what is inside the file — so the tooling stops before anything ever reaches the ECM. Send us the file you edited and we correct the checksums, then send it straight back: same tune, same tables, valid again.

When people order this

• Calterm or INSITE refuses the calibration after an edit, or reports a checksum / corrupt-file error.
• The write starts and aborts part-way, or the module rejects the file at the last step.
• A file came back from somebody else’s tool “already corrected” and still will not take.
• Two calibrations were merged, cut down or rebuilt and the file stopped validating.

What is covered

The Cummins ECM families we do this on routinely: CM2350, CM2450, CM871 and CM2250, and the .xcal calibrations that belong to them. On an older or unusual module, ask before you pay — we would rather say no in one message than take an order and stall on it.

What to send

• The edited .xcal — the file that will not validate.
• The original .xcal if you still have it. Not required, but it halves the guesswork and speeds the job up.
• The ECM code or calibration part number if you have it to hand (printed on the module, and shown by Calterm and INSITE).

How the order runs

1. Order this service. One order covers one file.
2. Send the file: reply to your receipt, or use the contact form (attachments up to 25 MB each).
3. A technician confirms which family and map area the file belongs to, corrects the checksums, and sends it back to the same address — usually within one business day.

Asked often

Does this change my tune? No. Only what has to change, changes. Every map you edited comes back exactly as you left it, byte for byte everywhere else.

Do you need the ESN or VIN? Not for this job. Nothing connects to the truck: it is file in, file out.

I have five files. Order one line per file, or ask us first and we will tell you what the batch comes to.

Will you tell me how it is calculated? No — that is the service. What we will tell you, honestly, is whether your file is inside what we do.

Related: Cummins .ECFG checksum correction · all checksum and decryption services. We work on tuning, calibration and file repair only — we do not remove or disable emissions equipment.