Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The On-Board Diagnostic (OBD II) System Check prompts the technician to complete some basic checks and to store the Freeze Frame and Failure Records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
2. If any component DTCs are set, diagnose those DTCs first. A fault in a component can cause the converter to appear degraded or may have caused its failure.
3. This step includes checks for conditions that can cause the three-way catalytic converter to appear degraded. Repair any problems found before proceeding with this table.
4. If the three-way catalytic converter needs to be replaced, make sure that another condition is not present which would cause the converter to become damaged. These conditions may include the following: misfire, high engine oil or coolant consumption, and/or retarded spark timing or weak spark. To avoid damaging the replacement converter, correct any possible causes of converter damage before replacing the catalytic converter.
5. Clearing DTCs allows the catalyst test to be run up to 6 times this ignition cycle. Once the ignition is cycled, the test will run only once. Driving the vehicle heats the catalyst to a test temperature. The ECM must see predetermined amount of time at above idle before allowing the catalyst test to run at idle. Once at idle, the ECM will allow the system to stabilize and then test the catalyst in 2 stages.
6. If no faults have been found at this point and no additional DTCs were set, refer to Diagnostic Aids for additional checks and information.