LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 1998 >> ES 300 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Tests >> DTC P0420: Catalyst System Efficiency Below Threshold (Except CALIFORNIA Models) >> Confirmation Test
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Confirmation Test

Connect Lexus scan tool to Data Link Connector (DLC) No. 3. See Figure. Ensure all accessories are turned off. Start and warm engine to normal operating temperature. Raise engine speed to 2500-3000 RPM for 3 minutes. Using Lexus scan tool, ensure heated oxygen sensors (bank 1 sensor 1 and bank 1 sensor 2) feedback to ECM fluctuates around .5 volts.

scientia non olet · About LEMON Manuals