If the file is just named "103" without ".rar," manually rename it by adding .rar to the end so your software recognizes it.
To access the files inside, you need a decompression utility: The official tool for .rar files.
If prompted for a password, common defaults for tech archives are 1234 , mhhauto , or the name of the website where you found the link. 3. Usage Guide (For OBD2 Firmware 103)