LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Suzuki >> 2011 >> Grand Vitara Base >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System Diagnosis >> Diagnostic Information and Procedures >> DTC P0420: Catalyst System Efficiency Below Threshold >> DTC Detecting Condition and Trouble Area
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC Detecting Condition and Trouble Area

P0420 DTC DETECTING CONDITION CHART

DTC detecting condition Trouble area
P0420: Catalyst System Efficiency Below Threshold 
Ratio of integrated value of HO2S output variation per integrated value of A/F sensor output variation is more than specification while vehicle is running after warmed up.
(2 D/C detection logic)
  • Exhaust gas leak
  • HO2S and/or its circuit
  • A/F sensor and/or its circuit
  • TWC
  • ECM