Heated Oxygen Sensor (Ho2S) Inspection: Notes

PID/DATA Monitor Inspection (HO2S)

1. Connect the M-MDS to the DLC-2.
2. Start the engine and warm it up completely.
3. Access the following PIDs using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST ).
   • VSS (Vehicle speed)
   • RPM (Engine speed)
   • O2S12 (HO2S output voltage)
4. Drive the vehicle and decelerate the engine speed by releasing the accelerator pedal fully when the engine speed is 3, 000 rpm or more.
5. Verify that the HO2S output voltage (PID: O2S12) changes as shown in the figure during deceleration. (outputs 0.6 V or more once or more, then 0.3 V or less).
   Fig 1: HO2S Output Voltage Graph

   Courtesy of MAZDA MOTORS CORP.
   • If not as verified, replace the HO2S. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION ).