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Home >> Hyundai >> 2001 >> Accent GL, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0422: Catalyst Efficiency Below Threshold >> Test Procedures

Test Procedures

  1. Check if DTC P0130, P0136 and/or P0141 is set. If any of listed DTCs are set in addition to P0442, repair those DTCs first. See DTC P0130 OR DTC P0136: HEATED OXYGEN SENSOR CIRCUIT MALFUNCTION  or DTC P0135 OR P0141: HEATED OXYGEN SENSOR HEATER CIRCUIT MALFUNCTION  . If none of listed DTCs are set in addition to P0442, go to next step.
  2. Start engine and allow to idle at normal operating temperature. Inspect for exhaust leaks upstream and downstream of catalytic converter. Inspect for exhaust leaks around front HO2S and rear HO2S. If no leaks are found, go to next step. If leaks are found, repair exhaust leaks. When repairs are completed, clear DTC and verify operation.
  3. Check rear HO2S operation. See DTC P0130 OR P0136: HEATED OXYGEN SENSOR CIRCUIT MALFUNCTION  . If rear HO2S is okay, go to next step. If rear HO2S is not okay, repair as necessary. When repairs are completed, clear DTC and verify operation.
  4. Turn ignition off. Replace catalytic converter and clear DTC P0422. Road test vehicle and check for DTCs. If DTC P0422 does not reset, repairs and inspection are complete. If DTC P0422 resets, ensure ECM connector and terminals are clean and tight. If ECM connector is okay, replace ECM. When repairs are completed, clear DTC and verify operation.
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