Note. Before performing any DIAGNOSTIC TEST, refer toWARNINGS, CAUTIONS and NOTES in DIAGNOSTIC TESTS .
Note. Testing individual components does not isolate shorts or opens. Perform all voltage tests using a Digital Volt-Ohmmeter Meter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use ohmmeter to isolate wiring harness shorts or opens.
Diagnostic Aids
Engine Control Module (ECM) evaluates catalytic converter storage capability by monitoring upstream Heated Oxygen Sensor (HO2S) and downstream HO2S performance, calculating a ratio based on the amplitude of the 2 signals and evaluating this information based on load and speed conditions. Malfunction code will set when ECM determines catalytic converter storage capability has degraded. Check for catalytic converter deterioration.