LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 1996 >> LX 450 >> Repair and Diagnosis >> External Pages >> Different car >> Section 7 (Engine Controls - Tests W/Codes) >> Diagnostic Testing >> Code P0420 - Catalyst System Efficiency Below Threshold >> Diagnosis & Repair
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnosis & Repair

WARNING: This page is about a different car, the 1995 Toyota Land Cruiser. However, it is still accessible from the selected car via links, so may be relevant.
  1. Connect scan tester. See Figure. Start and warm engine to normal operating temperature. Drive vehicle at 31-40 MPH for 5-10 minutes. Stop vehicle. Retrieve codes. See RETRIEVING TROUBLE CODES .
  2. If codes other than P0420 are present, diagnose and repair those codes first. If Code P0420 is only displayed, inspect oxygen sensor circuits. See CODE P0130  - HEATED OXYGEN SENSOR (RIGHT SIDE, NO. 1) CIRCUIT. Repair systems as needed. If oxygen sensor circuits and sensors are okay, replace catalytic converter and retest.
scientia non olet · About LEMON Manuals