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HOMESERVICE MANUALSMAZDA20086 S SPORT, 4D HATCHBACK, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 589 (ON-BOARD DIAGNOSTIC [ENGINE CONTROL SYSTEM L3 WITH TC])DTC P0421NOTES
2008 Mazda 6 s Sport, 4D Hatchback, Standard

DTC P0421: 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 DETECTION CONDITION AND POSSIBLE CAUSES

DTC P0421 Warm up catalyst system 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 number of inversions the rear side performs while the front side inverts for a specified number of times when the following monitoring conditions are met. The PCM detects the inversion ratio. If the inversion ratio is below the threshold, The PCM determines that the catalyst system has deteriorated.

    MONITORING CONDITIONS 

    • Engine speed: 1, 500-3, 000 RPM 
    • Calculated TWC temperature: above 400°C {752°F} 
    • LOAD: 15-48%  (at engine speed of 2, 000 RPM  )

Diagnostic support note 
  • This is an intermittent monitor (Catalyst).
  • The 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.
  • The DTC is stored in the PCM memory.
POSSIBLE CAUSE 
  • TWC deterioration or malfunction
  • Exhaust gas leakage
  • Loose front HO2S
  • Loose rear HO2S
  • PCM malfunction
RENDER: 1.0x

NO RELATED

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