Detects errors in data transmission or storage, ensuring the modified ECU map is safe to flash.

: In WinOLS, a valid checksum is typically indicated by a green status bar or text, while an incorrect one shows as red .

A checksum is a calculated value based on the total content of the ECU's data. It acts as a safety verify; when you modify maps—like fuel or ignition timing—the original checksum no longer matches the new data. A checksum plugin automatically recalculates this value so the ECU recognizes the modified file as valid. Official Sources for WinOLS Checksum Plugins