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Home >> Subaru >> 2005 >> Outback R VDC Limited >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 12 (Engine Controls - Engine (Diagnostics) (H4SO U5 (PZEV))) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P0043 Ho2S Heater Control Circuit Low (Bank 1 Sensor 3)

DTC P0043 Ho2S Heater Control Circuit Low (Bank 1 Sensor 3)

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

DTC DETECTING CONDITION: 

CAUTION: After repair or replacement of faulty parts, conduct Clear Memory Mode < Ref. to , OPERATION , Clear Memory Mode.> and Inspection Mode < Ref. to , OPERATION , Inspection Mode.>.

WIRING DIAGRAM: 

Fig 1: Wiring Diagram - DTC P0043 HO2S Heater Control Circuit Low (Bank 1 Sensor 3)
G03828994Courtesy of SUBARU OF AMERICA, INC.
DTC P0043 DIAGNOSTIC PROCEDURE

Step Check Yes No
1. CHECK CURRENT DATA. 
  1. Start the engine.
  2. Read the data of rear oxygen sensor heater current using Subaru Select Monitor or OBD-II general scan tool.
NOTE:
  • Subaru Select Monitor

    For detailed operation procedure, refer to the "READ CURRENT DATA FOR ENGINE". < Ref. to , SUBARU SELECT MONITOR . >

  • OBD-II general scan tool

    For detailed operation procedure, refer to the OBD-II general scan tool instruction manual .

 Is the measured value more than 0.2 A? Repair the connector.
NOTE: In this case, repair the following:
  • Poor contact in rear oxygen sensor connector
  • Poor contact in rear oxygen sensor connecting harness connector
  • Poor contact in ECM connector
 Go to step 2. 
2. CHECK OUTPUT SIGNAL FROM ECM. 
  1. Start and idle the engine.
  2. Measure the voltage between ECM connector and chassis ground.

    Connector & terminal 

    (B135) No. 2 (+) - Chassis ground (-): 

 Is the measured value less than 1 V? Go to step 5.  Go to step 3  .
3. CHECK OUTPUT SIGNAL FROM ECM. 
Measure the voltage between ECM connector and chassis ground.
Connector & terminal 
(B135) No. 2 (+) - Chassis ground (-): 		 Does the voltage change by shaking the ECM harness and connector? Repair poor contact in ECM connector. Go to step 4  .
4. CHECK OUTPUT SIGNAL FROM ECM. 
  1. Disconnect the connector from rear oxygen sensor.
  2. Measure the voltage between ECM connector and chassis ground.

    Connector & terminal 

    (B135) No. 2 (+) - Chassis ground (-): 

 Is the measured value less than 1 V? Replace the ECM. < Ref. to ENGINE CONTROL MODULE (ECM) . > Repair battery short circuit in harness between ECM and rear oxygen sensor connector. After repair, replace the ECM. < Ref. to ENGINE CONTROL MODULE (ECM) . >
5. CHECK POWER SUPPLY TO REAR OXYGEN SENSOR. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connector from rear oxygen sensor.
  3. Turn the ignition switch to ON.
  4. Measure the voltage between rear oxygen sensor connector and engine ground or chassis ground.

    Connector & terminal 

    (B19) No. 2 (+) - Chassis ground (-): 

 Is the measured value more than 10 V? Go to step 6  . Repair power supply line.
NOTE: In this case, repair the following:
  • Open circuit in harness between main relay and rear oxygen sensor connector
  • Poor contact in rear oxygen sensor connector
  • Poor contact in coupling connector
6. CHECK REAR OXYGEN SENSOR. 
  1. Turn the ignition switch to OFF.
  2. Measure the resistance between rear oxygen sensor connector terminals.

    Terminals 

    No. 3 - No. 2: 

 Check Is the measured value less than 30 Ω? Repair harness and connector.
NOTE: In this case, repair the following:
  • Open circuit in harness between rear oxygen sensor and ECM connector
  • Poor contact in rear oxygen sensor connector
  • Poor contact in ECM connector
  • Poor contact in coupling connector
 Replace the rear oxygen sensor. < Ref. to REAR OXYGEN SENSOR . >
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