HO2S Inspection

2011 Mazda CX-7 i Sport, 2.5 5SECTION HO2S Inspection
  1. Warm up the engine to normal operating temperature.
  2. Using the M-MDS, monitor the following:
    • Vehicle speed (PID: VSS)
    • Engine speed (PID: RPM)
    • HO2S voltage (PID: O2S12)
  3. Drive the vehicle and decelerate the engine speed by releasing the accelerator pedal fully when the engine speed is 3,000 RPM or more  .
  4. Verify that the HO2S outputs a voltage of 0.6 V or more  , one time or more, then verify that the HO2S voltage (PID: O2S12) is 0.3 V or less  while decelerating as shown in the illustration.
    Fig 1: HO2S Output Voltage Graph
    G06205251Courtesy of MAZDA MOTORS CORP.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.