LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 1995 >> Tercel Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Testing >> Code P0420 - Catalyst System Efficiency Below Threshold >> Circuit Description
September 30: LEMON manuals is back up on a temporary server! Slowness is possible

Circuit Description

The ECM compares waveform of oxygen sensor located before catalytic converter with waveform of oxygen sensor located after converter to determine if converter performance has deteriorated. If both waveforms change at similar rate, catalyst performance has deteriorated. Code is set when all oxygen sensors have same amplitude after vehicle is driven for 5 minutes at 19-52 MPH. Possible causes are:

scientia non olet · About LEMON Manuals