Subaru IMPREZA 2004 Service Manual page 395

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
2 CHECK FRONT OXYGEN (A/F) SENSOR
HEATER CURRENT.
1)Turn the ignition switch to OFF.
2)Repair the battery short circuit in harness
between ECM and front oxygen (A/F) sensor
connector.
3)Turn the ignition switch to ON.
4)Read the data of front oxygen (A/F) sensor
heater current using Subaru Select Monitor or
the OBD-II general scan tool.
NOTE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN(H4SO)(diag)-32, Subaru Select
Monitor.>
•OBD-II general scan tool
For detailed operation procedure, refer to the
OBD-II General Scan Tool Instruction Manual.
3 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 6 (+) — Chassis ground ( − − − − ):
(B136) No. 17 (+) — Chassis ground ( − − − − ):
Check
Is the current more than 2.3 A? Replace the ECM.
Does the voltage change by
shaking the ECM harness and
connector?
EN(H4SO)(diag)-86
Yes
END
<Ref. to
FU(H4SO)-47,
Engine Control
Module (ECM).>
Repair battery END
short circuit in har-
ness between
ECM and front
oxygen (A/F) sen-
sor connector.
No