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P1421 – Secondary Air Injection System Flow Malfunction (Cold Start)

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Symptoms

  • Cold start roughness
  • Emissions failure

Causes

  • Weak air pump
  • Blocked passages
  • Leaking hoses

Diagnosis

  • Command air pump
  • Inspect hoses
  • Check valves

Repair

  • Replace pump
  • Repair hoses
  • Clean passages
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