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HOMESERVICE MANUALSMAZDA20105 SPORT, 2.3 L, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 58 (ENGINE CONTROLS [SELF-DIAGNOSTICS 2.3L])DIAGNOSTIC TESTSDTC P0420: CATALYST SYSTEM EFFICIENCY - BELOW THRESHOLDDETECTION CONDITION
2010 Mazda 5 Sport, 2.3 L, Standard

Detection Condition

2010 Mazda 5 Sport, 2.3 L, StandardSECTION Detection Condition
WARNING: This page is about a different car, the 2003 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

PCM compares number of front HO2S and rear HO2S inversions for a predetermined time. PCM monitors number of inversions rear side performs while front side inverts for a specified number of times when following Monitoring Conditions are met. PCM detects inversion ratio. If inversion ratio is less than threshold, PCM determines catalyst system has deteriorated.

Monitoring Conditions:

  • Calculated load 15-50 percent (maximum calculated load value varies depending on engine speed)
  • Engine speed 1500-3000 RPM (MTX)
  • Engine speed 1410-3000 RPM (ATX)
This is an intermittent monitor (CATALYST). MIL illuminates if PCM detects malfunction condition in two consecutive drive cycles or in one drive cycle while DTC for same malfunction has been stored in PCM. PENDING CODE is available if PCM detects malfunction condition during first drive cycle. FREEZE FRAME DATA is available. DTC is stored in PCM memory.

RENDER: 1.0x

NO RELATED

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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.