1A-87 Engine General Information and Diagnosis:
DTC P0420: Catalyst System Efficiency below Threshold
S3RH0A1104042
System / Wiring Diagram
Circuit Description
ECM monitors oxygen concentration in the exhaust gas which has passed the 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 and three way catalytic converter.
Reference
Oscilloscope waveforms
C41 (31P)
G04 (24P)
G03 (17P)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
28 27
29
30
31
5
6
1
2
3
4
5
6
7
11
12
9
10
11
13 12
14
15
16
16
17
1
2
7
8
13
14
3
4
9
10
15
17
18
8
19
20
21
22
23
24
1
2
3
ECM
WHT
ORN
C41-10
C41-13
WHT
G04-13
ORN
4
5 V
I3RH0A110022-01
1. HO2S-1
3. Warm up three way catalytic converter
2. HO2S-2
4. Three way catalytic converter
I2RH01110102-01
Summary of Contents for Liana RH413
Page 2: ......
Page 4: ......
Page 6: ......
Page 336: ...1K 4 Exhaust System...
Page 456: ...3D 4 Propeller Shafts...
Page 553: ...Automatic Transmission Transaxle 5A 5 4WD I3RH0A510002 01 1 Transfer...
Page 1044: ...8B 119 Air Bag System...
Page 1049: ...Table of Contents 9 v Roof Molding Components 9M 1 Splash Guard If Equipped Components 9M 2...
Page 1278: ...9M 3 Exterior Trim...
Page 1300: ...Prepared by 1st Ed Nov 2003 2nd Ed Feb 2007...
Page 1301: ...19 mm 99500 54G10 01E 99500 54G10 01E SERVICE MANUAL VOLUME 1 OF 2 SERVICE MANUAL VOL 1 OF 2...
Page 1302: ...27 mm 99500 54G10 01E 99500 54G10 01E SERVICE MANUAL VOLUME 2 OF 2 SERVICE MANUAL VOL 2 OF 2...