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HOMESERVICE MANUALSMAZDA20086 S SPORT, 4D HATCHBACK, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 590 (ON-BOARD DIAGNOSTIC [ENGINE CONTROL SYSTEM (AJ])DTC P0421, P0431NOTES
2008 Mazda 6 s Sport, 4D Hatchback, Standard

DTC P0421, P0431: Notes

2008 Mazda 6 s Sport, 4D Hatchback, StandardSECTION Notes
WARNING: This page is about a different car, the 2007 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.
DTC P0421, P0431 [AJ] DETECTION CONDITION AND POSSIBLE CAUSES

DTC P0421 Warm-up catalyst system (RH) efficiency below threshold
DTC P0431 Warm-up catalyst system (LH) efficiency below threshold
DETECTION CONDITION 
  • The PCM compares the number of front HO2S and rear HO2S inversions for a predetermined time. The PCM monitors the rear HO2S inversion counts when the following conditions are met: The PCM detects inversion ratio. If the inversion ratio is below threshold, the PCM determine that catalyst system has deteriorated.
    • The front HO2S inversion counts is as prescribed when the following monitoring conditions are met:
    • The accumulated occurrence time of the following monitoring conditions has exceeded the prescribed time limit:

    MONITORING CONDITION 

    • The engine speed is 1,250-2,750 RPM  .
    • Calculated TWC temperature is above 400 °C {752 °F} 
    • The calculated load is 15-44% 

Diagnostic support note 
  • This is an intermittent monitor (Catalyst).
  • MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
  • PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.
  • DIAGNOSTIC MONITORING TEST RESULTS is available.
  • FREEZE FRAME DATA is available.
  • DTC is stored in the PCM memory.
POSSIBLE CAUSE 
  • WU-TWC deterioration or malfunction
  • Exhaust gas leakage
  • Looseness of HO2S (RF, LF, RR, LR)
  • PCM malfunction
RENDER: 1.0x

NO RELATED

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