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Home >> Toyota >> 2002 >> RAV4 Base, AWD, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 11 (Engine Control System Self-Diagnostics) >> Diagnostic Tests >> DTC P0420: Catalyst System Efficiency Below Threshold >> Diagnosis & Repair
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Diagnosis & Repair

WARNING: This page is about a different car, the 2002 Toyota MR2. However, it is still accessible from the selected car via links, so may be relevant.
  1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTC P0420 is displayed, go to next step. If any other DTCs are displayed, diagnose and repair those DTCs first.
  2. Check exhaust system for leaks. If problem does not exist, go to next step. If problem exists, repair as necessary.
  3. Check heated oxygen sensor No. 1. See DTC P0130: HEATED OXYGEN SENSOR CIRCUIT (BANK NO. 1 SENSOR NO. 1) OR P0150: HEATED OXYGEN SENSOR CIRCUIT (BANK NO. 2 SENSOR NO. 1) . If problem does not exist, go to next step. If problem exists, repair as necessary.
  4. Check heated oxygen sensor No. 2. See DTC P0136: HEATED OXYGEN SENSOR CIRCUIT (BANK NO. 1 SENSOR NO. 2) . If problem exists, repair as necessary. If problem does not exist, replace catalytic converter.
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