DTC P1498 Coil 4 EGR "A" Control Circuit Low: Notes

WARNING: This page is about a different variant/trim than selected.

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 Ref. to ENGINE (DIAGNOSTICS) (H4DO)>Clear Memory Mode . and Inspection Mode Ref. to ENGINE (DIAGNOSTICS) (H4DO)>Inspection Mode .
Use the check board when measuring the ECM terminal voltage and resistance.

Wiring diagram:

Engine Electrical System Ref. to WIRING SYSTEM>Engine Electrical System>WIRING DIAGRAM .

Fig 1: Engine Electrical System Wiring Diagram (EGR Control Circuit Low)

Courtesy of SUBARU OF AMERICA, INC.

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?
- Yes: Go to 2.
- No: 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
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; (B135) No. 12 - (E18) No. 3:

DTC P1494; (B135) No. 48 - (E18) No. 1:

DTC P1496; (B135) No. 25 - (E18) No. 4:

DTC P1498; (B135) No. 49 - (E18) No. 6:

Is the resistance less than 1 Ω?
- Yes: Go to 3.
- No: repair the harness and connector.
  NOTE:
  In this case, repair the following item:
  - Open circuit of harness between ECM connector and EGR control valve connector
  - Poor contact of coupling connector
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; (B135) No. 12 - Chassis ground:
  
  DTC P1494; (B135) No. 48 - Chassis ground:
  
  DTC P1496; (B135) No. 25 - Chassis ground:
  
  DTC P1498; (B135) No. 49 - Chassis ground:
  
  Is the resistance 1 MΩ or more?
  - Yes: Go to 4.
  - No: Repair ground short circuit of harness between ECM connector and EGR control valve connector.
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?
- Yes: Repair the poor contact of ECM or EGR control valve connector.
- No: Replace EGR control valve. Ref. to EMISSION CONTROL (AUX. EMISSION CONTROL DEVICES) (H4DO)>EGR Control Valve .