Subaru IMPREZA 2004 Service Manual page 399

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
E: DTC P0038 HO2S HEATER CONTROL CIRCUIT HIGH (BANK 1 SENSOR 2)
• DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4SO)(diag)-47,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)(diag)-40, OPERATION,
Inspection Mode.>.
• WIRING DIAGRAM:
MAIN RELAY
6
4
5
3
2
1
B47
B19 B22
1 2 3 4
2 1
5 6 7 8
4 3
9 10 11 12
B47
13 14 15 16
1 2
3 4
5 6
Step
1 CHECK INPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 4 (+) — Chassis ground ( − − − − ):
LHD
OXYGEN SENSOR
B: B135
C: B136
D: B137
F44
1 2 3 4
5 6 7 8
B137
1 2 3 4
5
6 7 8 9 10 11 12 13
14 15 16 17 18 19 20
EN(H4SO)(diag)-90
B61
F44
2 LHD
REAR
B19
ECM
B22
E3
E
B83
: RHD
1 2 3 4
B83
: LHD
1 2
1 2 3
7 8
4 5 6
18 19 20
Check
Is the voltage more than 8 V?
BATTERY
SBF-5
*
1
B83
LHD : 5
*
RHD : 4
2 3
1
8 9
10 11 12 13 14 15
B136
20 21 22 23
3 4 5 6
9 10 11 12 13 14 15 16 17
21 22 23 24 25 26
Yes
Go to step 2. Go to step 3.
E
B135
4 5 6 7
16 17 18 19
24 25 26 27 28
EN-01422
No