Subaru Legacy BN/BS (2015-2019) Service Manual: Dtc p0201 cylinder 1 injector "a" circuit

Subaru Legacy BN/BS (2015-2019) Service Manual / Engine (diagnostics)(h4do) / Diagnostic procedure with diagnostic trouble code (dtc) / Dtc p0201 cylinder 1 injector "a" circuit

DTC DETECTING CONDITION:

Immediately at fault recognition

TROUBLE SYMPTOM:

• Improper idling

• Poor driving performance

CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode Clear Memory Mode > OPERATION, and Inspection Mode Inspection Mode > PROCEDURE.

WIRING DIAGRAM:

• Engine Electrical System ENGINE TYPE FB (WITHOUT PUSH BUTTON START) Engine Electrical System > WIRING DIAGRAM

• Engine Electrical System ENGINE TYPE FB (WITH PUSH BUTTON START) Engine Electrical System > WIRING DIAGRAM

STEP	CHECK	YES	NO
1.CHECK POWER SUPPLY TO FUEL INJECTOR. 1) Turn the ignition switch to OFF. 2) Disconnect the connector from fuel injector. 3) Turn the ignition switch to ON. 4) Measure the voltage between fuel injector connector and the engine ground. Connector & terminal DTC P0201; (E5) No. 2 (+) — Engine ground (−): DTC P0202; (E16) No. 2 (+) — Engine ground (−): DTC P0203; (E6) No. 2 (+) — Engine ground (−): DTC P0204; (E17) No. 2 (+) — Engine ground (−):	Is the voltage 10 V or more-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0201 CYLINDER 1 INJECTOR "A" CIRCUIT	Repair the harness and connector. NOTE: In this case, repair the following item: • Open circuit in harness between main relay and fuel injector connector • Poor contact of main relay connector • Poor contact of coupling connector
2.CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR. 1) Turn the ignition switch to OFF. 2) Disconnect the connector from ECM. 3) Measure the resistance between fuel injector connector and engine ground. Connector & terminal DTC P0201; (E5) No. 1 — Engine ground: DTC P0202; (E16) No. 1 — Engine ground: DTC P0203; (E6) No. 1 — Engine ground: DTC P0204; (E17) No. 1 — Engine ground:	Is the resistance 1 M- or more-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0201 CYLINDER 1 INJECTOR "A" CIRCUIT	Repair the short circuit to ground in harness between ECM connector and fuel injector connector.
3.CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR. Measure the resistance of harness between ECM connector and fuel injector connector. Connector & terminal DTC P0201; (E158) No. 23 — (E5) No. 1: DTC P0202; (E158) No. 8 — (E16) No. 1: DTC P0203; (E158) No. 9 — (E6) No. 1: DTC P0204; (E158) No. 22 — (E17) No. 1:	Is the resistance less than 1 --	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0201 CYLINDER 1 INJECTOR "A" CIRCUIT	Repair the open circuit of the harness between the ECM connector and fuel injector connector.
4.CHECK FUEL INJECTOR. Measure the resistance between fuel injector terminals on the corresponding cylinder. Terminals No. 1 — No. 2:	Is the resistance 5 — 20 --	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0201 CYLINDER 1 INJECTOR "A" CIRCUIT	Replace the fuel injector. Fuel Injector
5.CHECK FOR POOR CONTACT. Check for poor contact of ECM connector.	Is there poor contact of ECM connector-	Repair the poor contact of ECM connector.	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0201 CYLINDER 1 INJECTOR "A" CIRCUIT
6.CHECK FUEL INJECTOR OPERATION. 1) Connect all connectors. 2) Start the engine. 3) Check if the corresponding fuel injector emits operating sound. NOTE: Use a sound scope to check the operating sound.	Does the fuel injector emit operating sound-	Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again. NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.	Repair the poor contact of fuel injector connector.

1. OUTLINE OF DIAGNOSIS

Based on the self-diagnostic result of the injector driving IC, judge the injector driving circuit as normal or abnormal.

Injector driving IC detects the status of “fuel remains injected” or “fuel is not injected” as a malfunction.

2. EXECUTION CONDITION

Secondary Parameters	Execution condition
Battery voltage	≥ 10.9 V
Elapsed time after starting the engine	> 1 s
Engine speed	> 500 rpm
Injection status	Not during fuel cut

3. GENERAL DRIVING CYCLE

Perform the diagnosis continuously after the enable conditions have been established.

4. DIAGNOSTIC METHOD

Judge as NG when the following conditions are established.

Judgment Value

Malfunction Criteria	Threshold Value
Injector driving IC information	Trouble

Time Needed for Diagnosis: 256/1000 seconds - 10 time(s)

Malfunction Indicator Light Illumination: Illuminates as soon as a malfunction occurs.

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