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/Transaxle Control Module (E/TCM) or 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. Code will set when E/TCM or ECM determines catalytic converter storage capability has degraded. Check for catalytic converter deterioration.