July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Engine Control Module (ECM)

Courtesy of HYUNDAI MOTOR AMERICA

Engine Control Module (ECM) malfunctions are detected by using a checksum technique for verifying data. The digital data is composed of zero and ones. A checksum is the total of all ones in a string of data. By comparing the checksum value with a stored value, a malfunction can be detected.