LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Infiniti >> 2002 >> G20 Automatic, RE4F03W >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - G20 >> Diagnostic Tests >> DTC P0420: 3-Way Catalyst Function >> DTC Confirmation Test (Using Generic Scan Tool)
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC Confirmation Test (Using Generic Scan Tool)

NOTE: Use the following test to check overall function of 3-way catalyst. During this test, 1st trip DTC may not be confirmed.
CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  1. Start engine and drive vehicle at a speed of more than 43 MPH for 2 consecutive minutes. Stop vehicle and leave engine running. Measure voltage between engine ground and front HO2S signal circuit at ECM terminal No. 62 (White wire), then rear HO2S signal circuit at ECM terminal No. 63 (White wire) by backprobing. See Figure and Figure .
  2. Increase engine speed to 2000 RPM. If switching frequency of rear HO2S is less than 75 percent of front HO2S switching frequency, catalyst is operating properly. If switching frequency of rear HO2S is not less than 75 percent of front HO2S switching frequency, go to DIAGNOSTIC PROCEDURE . If front HO2S does not switch more than 5 times within 10 seconds, diagnose and repair front HO2S. See DTC P0133: FRONT HEATED OXYGEN SENSOR (HO2S) .
scientia non olet · About LEMON Manuals