Description of On-Board Diagnostics
HOW THE ON-BOARD DIAGNOSTIC SYSTEM OPERATESThe Engine Control Unit (ECU) monitors input and output circuits within the fuel injection system. Some circuits are checked continually, others are only checked under certain conditions (starting, etc.). If the OBD system determines that one of the circuits is malfunctioning, a fault code will be stored in memory. Each circuit has its own fault number and message. Refer to fault numbers and parameters. It is important to note that fault codes will stay in memory as long as there is battery power to the ECU, terminal 103. Therefore, it is impossible to tell when a fault code has been set.