LAUNCH TECH USA 1-877-528-6249 SUPPORT@LAUNCHTECHUSA.COM

Some users feedback they have a same problem with Ktag and/or Kess v2 Master checksums error eg. the units will not calculate checksums when loading files. And this error happens on both Chinese clone Ktag/Kess and EU clone ones.

Then why Ktag / Kess checksums error and how to prevent it happens?

At first, I also have this error, but finally I find out the reason, and I hope I share here to help others.

Let’s go!

According to this ECU, you must do a full read and then straight after that you must do a full write. After you’ve done that, the ECU is open for you to load your tunes based on partial reads and writes. The reason for the full read and full write is that it takes off the tuning protection on the ECU.

I did a full read a month ago, and only did a full write a week ago. Whenever I tried to write the tune file, the ECU would be bricked and come back with a checksum error after the write. So the secret is to do the write directly after the read. I did this with a FGTECH V54 but the process is the same for Kess. I now write my custom tunes with Kess to the ECU, and KSuite corrects the checksums for the partial writes.

The process is different for other ECUs I’d imagine.