DTC P2198: A/F/O2 Sensor Signal Biased/Stuck Rich Bank 2 Sensor 1: Notes

DTC detecting condition:

Detected when two consecutive driving cycles with fault occur.

CAUTION: After servicing or replacing faulty parts, perform Clear Memory Mode Ref. to ENGINE (DIAGNOSTICS) (H6DO)>Clear Memory Mode>OPERATION , and inspection mode Ref. to ENGINE (DIAGNOSTICS) (H6DO)>Inspection Mode>PROCEDURE .

Wiring diagram:

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

Courtesy of SUBARU OF AMERICA, INC.

CHECK FRONT OXYGEN (A/F) SENSOR CONNECTOR AND COUPLING CONNECTOR.
Check the front oxygen (A/F) sensor connector and coupling connector.

Has water entered the connector?

Yes: Completely remove any water inside.

No: Go to 2
CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR CONNECTOR.
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
3. Measure the resistance between ECM connector and chassis ground.
  Connector & terminal
  
  (E158) No. 45 - Chassis ground:
  
  (E158) No. 44 - Chassis ground:
Is the resistance 1 MΩ or more?

Yes: Go to 3

No: Repair the short circuit to ground in harness between ECM connector and front oxygen (A/F) sensor connector.
CHECK OUTPUT SIGNAL FOR ECM.
1. Connect the connector to ECM.
2. Turn the ignition switch to ON.
3. Measure the voltage between ECM connector and chassis ground.
  Connector & terminal
  
  (E158) No. 45 (+) - Chassis ground (-):
Is the voltage 4.5 V or more?

Yes: Go to 5

No: Go to 4
CHECK OUTPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector and chassis ground.

Connector & terminal

(E158) No. 44 (+) - Chassis ground (-):

Is the voltage 4.95 V or more?

Yes: Go to 5

No: Replace the front oxygen (A/F) sensor. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H6DO)>FRONT OXYGEN (A/F) SENSOR
CHECK OUTPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector and chassis ground.

Connector & terminal

(E158) No. 45 (+) - Chassis ground (-):

(E158) No. 44 (+) - Chassis ground (-):

Is the voltage 8 V or more?

Yes: Repair the short circuit to power in the harness between ECM connector and front oxygen (A/F) sensor connector. After repair, replace the ECM. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H6DO)>ENGINE CONTROL MODULE (ECM)

No: Repair the poor contact of ECM connector.