Subaru Legacy 2003 Service Manual page 1907

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
6 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B137) No. 4 (+) — Chassis ground ( − − − − ):
(B137) No. 5 (+) — Chassis ground ( − − − − ):
Is the measured value less than the specified
value shaking harness and connector of ECM
while monitoring the value with voltage meter?
7 CHECK FRONT OXYGEN (A/F) SENSOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between front oxy-
gen (A/F) sensor connector terminals.
Terminals
No. 2 — No. 1:
Is the measured value less than the speci-
fied value?
Step
EN(H4DOSTC)-68
Value
1.0 V
10 Ω
Yes
Repair the poor Go to step 7.
contact in ECM
connector.
Repair the har- Replace the front
ness and connec- oxygen (A/F) sen-
tor. sor. <Ref. to
FU(H4DOSTC)-
NOTE:
38, Front Oxygen
In this case, repair
(A/F) Sensor.>
the following:
• Open or ground
short circuit in har-
ness between
front oxygen (A/F)
sensor and ECM
connector
• Poor contact in
front oxygen (A/F)
sensor connector
• Poor contact in
ECM connector
No