Dtc P0420: Catalyst System Efficiency Below Threshold - Suzuki SX4 Service Manual

1A-124 Engine General Information and Diagnosis:

DTC P0420: Catalyst System Efficiency below Threshold

System and Wiring Diagram
BLU WHT
1
3
15 14 13 12 11
30 29 28 27 26
44
45 43 42 41
59
60 58 57 56
1. HO2S-1
2. HO2S-2
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 HO2S-1 output voltage because of the amount of oxygen in the exhaust gas
which has been stored in warm up three way catalytic converter.
DTC Detecting Condition and Trouble Area
DTC detecting condition
• While vehicle running at constant speed under other than high load.
• Time from rich or lean switching command is output till HO2S-2
output voltage crosses 0.45 V is less than specified value.
(2 driving cycle detection logic, monitoring once / 1 driving)
ORN
WHT BLU
2
E01
10 9 8 7 6 5 4 3
25 24 23 22 21 20 19 18
40 39 38 37 36 35 34 33
55 54 53 52 51 50 49 48
3. Warm up three way catalytic converter
4. Three way catalytic converter
WHT
ORN
BRN
4
2 1 15 14 13 12 11
17 16 30 29 28 27 26
44
32 31 45 43 42 41
59
47 46 60 58 57 56
• Exhaust gas leak
• Warm up three way catalytic converter
malfunction
• HO2S-2 malfunction
• HO2S-1 malfunction
5
C01-10
C01-57
5 V
C01-11
C01
10 9 8 7 6 5 4 3
25 24 23 22 21 20 19 18
40 39 38 37 36 35 34 33
55 54 53 52 51 50 49 48
5. ECM
Trouble area
S7RW0A1104047
2 1
17 16
32 31
47 46
I6RW0D110038-01