OBD-II System Readiness Tests (Monitors)

In some areas of the country, it may become a legal requirement to pass an Inspection/Maintenance (I/M) test of the OBD-II system. Before I/M testing can proceed, all System Readiness Tests (SRT) must show a YES status on scan tool. Follow scan tool manufacturer's instructions.

During the mix of city and highway driving involved in the OBD-II drive cycle, the diagnostic tests (monitors) will test certain parts of the OBD-II software and hardware used to control vehicle emissions. Some tests will run to completion and will indicate a YES or NO, others such as misfire or fuel injection system test, will run continuously. See SRT STATUS  table.

If a fault exists in the system being tested, a DTC will be stored in PCM memory. Depending on type of fault detected, some DTCs will command Malfunction Indicator Light (MIL) to illuminate immediately. Other faults will cause PCM to store DTC in memory along with freeze frame information but will not illuminate MIL until fault is detected again on a subsequent trip (second trip). Anytime a DTC is set in PCM memory or a repair is made and DTCs are cleared from PCM memory, I/M ready monitors will reset to "NO". To reset I/M monitors to a ready status, an OBD-II drive cycle must be performed. See OBD-II DRIVE CYCLE .