Dtc P0420: Catalyst System Efficiency Below Threshold - Suzuki Grand Vitara Service Manual

DTC P0420: Catalyst System Efficiency below Threshold

System and Wiring Diagram
BLU WHT
1
3
1. A/F sensor 3. Warm up three way catalytic converter
2. HO2S-2 4. Three way catalytic converter
Circuit Description
ECM monitors oxygen concentration in the exhaust gas which has passed the warm up three way catalytic converter
by HO2S-2. When the catalyst is functioning properly, the variation cycle of HO2S-2 output voltage (oxygen
concentration) is slower than that of A/F sensor output signal because of the amount of oxygen in the exhaust gas
which has been stored in warm up three way catalytic converter.
A/F Sensor Description
Refer to "A/F Sensor Description: ".
DTC Detecting Condition and Trouble Area
DTC detecting condition
Ratio of integrated value of HO2S-2 output variation per integrated
value of A/F sensor output variation is more than specification while
vehicle is running constant speed and low engine load after warmed
up.
(*2 driving cycle detection logic, monitoring once / 1 driving)
Engine General Information and Diagnosis:
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WHT BLU
2
4
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5
WHT C37-38
BLK
C37-37
YEL
C37-57
5 V
BRN C37-11
5. ECM
Trouble area
• Exhaust gas leak
• Warm up three way catalytic converter
malfunction
• HO2S-2 malfunction
• A/F sensor malfunction
1A-138
S5JB0A1104044
5 V
I5JB0A110053-02