This bulletin is being revised to add models, model years and additional information on emission testing. Please discard Corporate Bulletin Number 00-06-04-033A (Section 06 - Engine-Engine Controls).
Several states require that vehicles pass OBD system l/M emissions inspection. These inspections may apply to any 1996 and newer model year OBD II equipped passenger cars and light duty trucks.
As part of an OBD I/M emission inspection, the vehicle's I/M readiness status is checked to ensure that the vehicle's OBD system has properly evaluated the emissions systems of the vehicle for proper operation. To ensure vehicles are capable of passing this portion of the inspection, technicians can review the l/M readiness test status using the l/M System Status display on the Tech®2. This display provides test data that will verify whether the vehicle's OBD systems have run. States performing inspections on an advisory basis will not reject vehicles for not being I/M-ready.
Each OBD II system requires at least one diagnostic test. A system monitor is complete when all of the DTCs that report to the system monitor have run and passed or failed. The results of a failed test are reported by a diagnostic trouble code (DTC).
Once all of the tests are complete, the l/M System Status display indicates YES in the "Completed" column. For example, when the HO2S Heater Test indicates YES, all oxygen sensor heaters have been diagnosed.
When any required test for a specified system has not run, the "Completed" column under l/M System Status displays NO. The following is a list of conditions that would set the l/M System Status indicator to NO:
The OBD II System monitors all emission control systems that are on-board. Not all vehicles have a full complement of emission control systems. For example, a vehicle may not be equipped with AIR or EGR.
The following is a complete list of the vehicle's systems that may require monitoring by the OBD system:
If a specific vehicle is not required to monitor one or more of the above listed systems, the Tech®2 display will read "not supported." Any non-supported system will not be considered when determining the readiness of the overall system.
For the specific DTCs related to each system, refer to SI (Service Information) for further diagnostic information on conditions for running the DTC or refer to the publication information mentioned in this bulletin to order the Inspection Maintenance Emissions Diagnostics Manual and follow the I/M Readiness Testing System DTC Tables. Systems such as fuel delivery, misfire, and comprehensive components may not be listed in a system status list. These tests run continuously on some vehicles and may not require an indicator.
The l/M System Status display indicates when the control module has completed the required tests. This does not necessarily mean that the test has passed, only that a decision was made. If the diagnostic fails, a DTC will indicate the failure. If a failure indication is present, it may prevent other required tests from running. For example, a DTC for the control circuit of the relay controlling an AIR pump may not be listed in the Inspection Maintenance System DTC Table because it is a continuous test. If this DTC is set, the Active Tests for the AIR system may not run and AIR system readiness could display "NO."
The l/M System Status information may be useful for a technician to determine if diagnostics have run when verifying repairs.
The purpose of the Inspection/Maintenance (I/M) Complete System Set Procedure is to satisfy the enable criteria necessary to execute all of the I/M readiness diagnostics, and complete the trips for those particular diagnostics. When all diagnostic tests are completed, the I/M System Status indicators are set to YES. Perform this test when more than one of the I/M System Status indicators are set to NO.
That is right, First time get on the freeway and go 10 miles at a steady speed, then turn around and come back 10 miles. This should learn the O2 Sensors. Then let it sit over night. Drive again on the freeway 10 miles, same as the first trip. On the 3rd, start and drive in town and on a road that you can do 25 to 40. stop and go is ok. Try to go 4 mins at a steady speed some time in this trip. If you are in California, you do not need to reset all of the flags to get a shog test. Only a majority, 3 out of 5. or 3 out of 4. The evap test can take along time to run and pass.Your local shop can look at the I/M flags to see how may have run and passed.