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HOMESERVICE MANUALSMAZDA20086 S SPORT, 4D HATCHBACK, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 147 (EMISSION SYSTEM)THREE-WAY CATALYTIC CONVERTER (TWC) INSPECTIONNOTES
2008 Mazda 6 s Sport, 4D Hatchback, Standard

Three-Way Catalytic Converter (TWC) Inspection: Notes

2008 Mazda 6 s Sport, 4D Hatchback, StandardSECTION Notes
WARNING: This page is about a different car, the 2004 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
  • Make sure that no HO2S DTCs have been detected. If detected, this inspection is not applicable for TWC inspection.
  1. Connect the WDS or equivalent and monitor the following PIDs.
    • Monitor the right TWC using O2S11 PID for upstream HO2S and O2S12 PID for downstream HO2S.
  2. Begin to monitor the appropriate PIDs.
  3. Drive the vehicle for 10 min  at 65-96 km/h {40-60 mph}  to allow the front catalytic converter to reach operating temperature.
  4. Stop the vehicle and leave it in a safe place.
  5. Idle the engine.
  6. Record PIDs for 1 min. 
    Fig 1: Inversion Graph (Example)
    G01026446Courtesy of MAZDA MOTORS CORP.
  7. Select the appropriate PIDs and read the graph.
  8. Count the number of times (inversions) that the upstream HO2S graph line actually crosses the 0.5 V  line.
  9. Count the number of times (inversions) that the downstream HO2S graph line actually crosses the 0.5 V  line.
    NOTE:
    • Do not count the number of peaks. Refer to the graph.
  10. Using the following equation, calculate the value of ratio.

Equation 

RATIO = Upstream HO2S inversion / downstream HO2S inversion 

  • If the ratio is 1.5  or more, or there is no downstream HO2S inversion, the TWC is functioning properly.
  • If the ratio is less than 1.5  , the TWC is not functioning properly. Replace the TWC.
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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.