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Home >> Toyota >> 2004 >> Matrix Base, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 106 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0420: Catalyst System Efficiency Below Threshold (Bank 1) Or DTC P0430: Catalyst System Efficiency Below Threshold (Bank 2) >> Diagnosis & Repair
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Diagnosis & Repair

WARNING: This page is about a different car, the 2003 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If only DTC P0420 or P0430 is displayed, go to next step. If other codes are displayed, diagnose and repair those codes first and retest.
  2. Check for exhaust leaks. Repair as necessary. If exhaust system is okay, check heated oxygen sensor circuits (bank No. 1, sensor No. 1 and bank No. 2, sensor No. 1). See DTC P0130, DTC P0150, DTC P2195, DTC P2196, DTC P2197 OR P2198  test. Repair as necessary. If no problems are indicated, go to next step.
  3. Check heated oxygen sensor circuits (bank No. 1, sensor No. 2 and bank No. 2, sensor No. 2). See DTC P0136, DTC P0156, DTC P2270, DTC P2271, DTC P2272 OR DTC P2273  test. Repair as necessary. If oxygen sensor circuits are okay, replace catalytic converter and retest.
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