Subaru Legacy BN/BS (2015-2019) Service Manual: Dtc p1498 coil 4 egr "a" control circuit low

Subaru Legacy BN/BS (2015-2019) Service Manual / Engine (diagnostics)(h4do) / Diagnostic procedure with diagnostic trouble code (dtc) / Dtc p1498 coil 4 egr "a" control circuit low

DTC DETECTING CONDITION:

Immediately at fault recognition

TROUBLE SYMPTOM:

• Improper idling

• Poor driving performance

• Engine breathing

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 EGR CONTROL VALVE. 1) Turn the ignition switch to OFF. 2) Disconnect the connector from the EGR control valve. 3) Turn the ignition switch to ON. 4) Measure the voltage between EGR control valve connector and engine ground. Connector & terminal (E18) No. 2 (+) — Engine ground (−): (E18) No. 5 (+) — Engine ground (−):	Is the voltage 10 V or more-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P1498 COIL 4 EGR "A" CONTROL CIRCUIT LOW	Repair the harness and connector. NOTE: In this case, repair the following item: • Open circuit in harness between EGR control valve and main relay connector • Poor contact of coupling connector
2.CHECK HARNESS BETWEEN ECM AND EGR CONTROL VALVE CONNECTOR. 1) Turn the ignition switch to OFF. 2) Disconnect the connector from ECM. 3) Measure the resistance between ECM connector and EGR control valve connector. Connector & terminal DTC P1492; (E158) No. 12 — (E18) No. 3: DTC P1494; (E158) No. 48 — (E18) No. 1: DTC P1496; (E158) No. 25 — (E18) No. 4: DTC P1498; (E158) No. 49 — (E18) No. 6:	Is the resistance less than 1 --	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P1498 COIL 4 EGR "A" CONTROL CIRCUIT LOW	Repair the open circuit of the harness between the ECM connector and EGR control valve connector.
3.CHECK HARNESS BETWEEN ECM AND EGR CONTROL VALVE CONNECTOR. 1) Disconnect the connector from ECM. 2) Measure the resistance between ECM connector and chassis ground. Connector & terminal DTC P1492; (E158) No. 12 — Chassis ground: DTC P1494; (E158) No. 48 — Chassis ground: DTC P1496; (E158) No. 25 — Chassis ground: DTC P1498; (E158) No. 49 — Chassis ground:	Is the resistance 1 M- or more-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P1498 COIL 4 EGR "A" CONTROL CIRCUIT LOW	Repair ground short circuit of harness between ECM connector and EGR control valve connector.
4.CHECK FOR POOR CONTACT. Check for poor contact between ECM connector and EGR control valve connector.	Is there poor contact in ECM or EGR control valve connector-	Repair the poor contact of ECM or EGR control valve connector.	Replace EGR control valve. EGR Control Valve

1. OUTLINE OF DIAGNOSIS

NOTE:

For the detection standard, refer to DTC P1492. Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P1492 COIL 1 EGR "A" CONTROL CIRCUIT LOW

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Other materials:

Inspection
1. Visually check the cam carrier filter, and if clogging is found, replace with a new part.2. Check the camshaft journals for damage and wear. Replace the camshaft if faulty.3. Check the cam face condition of camshaft, and remove the minor faults by grinding with oil stone. Replace the camshaft if ...