Subaru 2002 IMPREZA Service Manual page 1356

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
AQ:DTC P0420 — CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD —
• DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• TROUBLE SYMPTOM:
• Engine stalls.
• Idle mixture is out of specifications.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(TURBO)-45, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(TURBO)-42, Inspection Mode.> .
• WIRING DIAGRAM:
MAIN RELAY
6
4
5
3
2
1
B47
1 LHD : 2
*
RHD : 4
LHD : 6
2
*
RHD : 1
LHD : 2
3
*
RHD : 1
LHD : 1
4
*
RHD : 2
5 LHD : 3
*
RHD : 4
6 LHD : 4
*
RHD : 3
B18 B19
1 2 1 2
3 4 3 4
(LHD)
2 1
4 3
(RHD)
REAR OXYGEN
SENSOR
B19
RHD
B260
B259
1
*
2
*
B83
RHD
A: B:
B134
F44 B47
1 2
1 2 3 4
3 4
5 6 7 8
5 6
1 2 3 4 5 6
EN(TURBO)-196
LHD 2 LHD
F61 F44
FRONT OXYGEN
(A/F) SENSOR
B18
C: D: B137 ECM
B135 B136
B83 B259
1 2 3
1 2
1 2 3 4
4 5 6
8 9
(LHD)
16 17
(RHD)
1 2
8 9 10 11 12
17 18 19 20 21
BATTERY
B134
5 6 7 1 2 3 4
10 11 12 13 14 15 10 11 12 13 14 15
18 19 20 21 22 22
20 21
B136
1 2 3 4
3 4 5 6 7
13 14 15 16 10 11 12 13 14 15 16 17
22 23 24 22 23 24 25 26
E
B135
5 6 7 8 9
16 17 18 19
23 24 25 26 27 28
B137
5 6 7 8 9
18 19 20 21
27 28 29 30 31
EN1439