Subaru 2002 IMPREZA Service Manual page 524

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
Step
8 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 23 (+) — Chassis ground ( − − − − ):
9 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. 5:
Check
Does the voltage change less
than 1.0 V by shaking harness
and connector of ECM while
monitoring the value with volt-
age meter?
Is the resistance less than 10
Ω?
EN-92
Yes
Repair the poor Go to step 9.
contact in ECM
connector.
Repair the har- Replace the front
ness and connec- oxygen (A/F) sen-
tor. sor. <Ref. to FU-
54, Fuel.>
NOTE:
In this case, repair
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