DTC Confirmation Test (Overall Function Check)

Malfunction is detected when 3-way catalyst does not operate properly. Start engine and drive vehicle at 43 MPH or more for 2 consecutive minutes. Stop vehicle and leave engine running. Measure voltage between ground and ECM harness connector terminals No. 50 (right front HO2S), or No. 51 (left front HO2S) and No. 56 (right rear HO2S), or No. 57 (left rear HO2S). Increase engine speed to 2000 RPM. Switching frequency of rear HO2S should be less than 75 percent of front HO2S switching frequency. If front HO2S does not switch more than 5 times within 10 seconds, diagnose front HO2S first. See DTC P0133 OR P0153: FRONT HEATED OXYGEN SENSOR .