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Home >> Ford >> 2015 >> Explorer Limited, 3.5L Eng VIN 8, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls (Except Diesel & Hybrid) - Pinpoint Tests DN - FD >> Pinpoint Test DW: Heated Oxygen Sensor (HO2S) >> Test Procedure

Test Procedure

  1. DW1 CHECK FOR DTCS 

    Are DTCs P0036, P0037, P0038, P0041, P0054, P0056, P0060, P00D2, P0136, P0137, P0138, P0139, P013A, P013B, P013C, P013E, P0140, P0141, P014A, P0157, P0158, P0159, P0161, P2A01 or P2A04 present? 

    Yes No
    GO to DW2  . RETURN to SYMPTOM CHARTS for further direction.
  2. DW2 VISUALLY INSPECT THE HO2S HARNESS 
    • Ignition OFF.
    • Verify the HO2S connectors are connected to the correct engine bank.
    • Visually inspect for:
      • crossed sensor wires
      • pinched, shorted, and corroded wiring and pins
      • oil or water contamination
      • damaged HO2S

    Is a concern present? 

    Yes No
    REPAIR as necessary.
    Clear the PCM DTCs. REPEAT the self-test.    		 For DTC P0041, GO to DW3  .
    For DTCs P013A, P013C, P013E or P014A, GO to  DW6.
    For DTCs P0036, P0037, P0038, P0054, P0056, P0060, P0141 or P0161, GO to  DW12.
    For all others, GO to  DW5.
  3. DW3 CARRY OUT THE KOER SELF-TEST 
    • Engine at normal operating temperature.
    • Carry out the PCM KOER self-test.

    Is DTC P0041 present? 

    Yes No
    GO to  DW8. GO to DW4  .
  4. DW4 CHECK FOR A SOURCE OF POTENTIAL HO2S CONTAMINATION 
    • Investigate the following items as potential sources of HO2S contamination:
      • use of unapproved silicon sealers
      • fuel contaminated by silicon additives
      • excessive oil consumption
      • glycol leaking internally in the engine
      • contaminated fuel
      • short drive cycles in cold weather
      • use of unapproved cleaning agents

    Is a concern present? 

    Yes No
    REPAIR the source of the contamination.
    CHANGE the engine oil and oil filter.
    RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
    REPEAT the self-test.    		 GO to DW5  .
  5. DW5 CHECK FOR UNMETERED AIR LEAKS 
    NOTE: Fuel calculations can be affected by unmetered air leaks.
    • Carefully inspect the following areas for potential air leaks:
      • hoses connecting to the mass air flow (MAF) sensor assembly
      • hoses connecting to the throttle body
      • intake manifold gasket leaks
      • positive crankcase ventilation (PCV) system
      • the vacuum lines are disconnected
      • incorrectly seated engine oil dipstick, tube or oil fill cap

    Are any air leaks present? 

    Yes No
    REPAIR the source of the air leak. RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
    REPEAT the self-test.    		 GO to DW6  .
  6. DW6 CHECK FOR EXHAUST SYSTEM CONCERNS 
    NOTE: Pressure above 241 kPa (35 psi) can cause damage to system components. Regulate the shop air to 34.4 kPa (5 psi) before connecting to the system.
    • Pressurize the exhaust system at the exhaust pipe outlet with 34.4 kPa (5 psi) regulated shop air.
    • Check the exhaust system for leaks using a soap and water solution.
    • Apply the soap and water solution to the following areas:
      • exhaust flanges and gaskets
      • universal HO2S and mounting surface
      • downstream HO2S and mounting surface

    Is a concern present? 

    Yes No
    For DTCs P013A, P013C, P013E or P014A, REPAIR as necessary.
    CARRY OUT the HO2S and Catalyst OBD Monitor Drive Cycle Procedures. REFER to ON BOARD DIAGNOSTIC (OBD) DRIVE CYCLE .
    Clear the PCM DTCs. REPEAT the self-test.
    For all others, REPAIR as necessary.
    Clear the PCM DTCs. REPEAT the self-test.    		 For DTCs P013A, P013C, P013E or P014A, INSTALL a new HO2S. REFER to the service information , Electronic Engine Controls.
    CARRY OUT the HO2S and Catalyst OBD Monitor Drive Cycle Procedures. REFER to ON BOARD DIAGNOSTIC (OBD) DRIVE CYCLE .
    Clear the PCM DTCs. REPEAT the self-test.
    For all others, GO to DW7  .
  7. DW7 CHECK FOR FUEL SELECTION CONCERNS 
    • Verify with the customer that flex fuel is not being used on a non-flex fuel vehicle.

    Is a concern present? 

    Yes No
    REPAIR as necessary.
    Clear the PCM DTCs. REPEAT the self-test.    		 GO to DW8  .
  8. DW8 CHECK THE HO2S CIRCUITS FOR AN OPEN 
    NOTE: Check both halves the HO2S connector for any water contamination.
    • Ignition OFF.
    • PCM connector disconnected.
    • For HO2S12,
    • HO2S12 connector disconnected.
    • Measure the resistance between:
      (+) HO2S12 Connector, Harness Side (-) PCM Connector, Harness Side
      HO2S12 HO2S12
      SIGRTN SIGRTN
    • For HO2S22,
    • HO2S22 connector disconnected.
    • Measure the resistance between:
      (+) HO2S22 Connector, Harness Side (-) PCM Connector, Harness Side
      HO2S22 HO2S22
      SIGRTN SIGRTN

    Are the resistances less than 5 ohms? 

    Yes No
    GO to DW9  . REPAIR the open circuit. Clear the PCM DTCs.
    REPEAT the self-test.
  9. DW9 CHECK THE HO2S CIRCUIT FOR A SHORT 
    • For HO2S12,
    • Measure the resistance between:
      (+) HO2S12 Connector, Harness Side (-) HO2S12 Connector, Harness Side
      HO2S12 SIGRTN
      HO2S12 VPWR
    • Measure the resistance between:
      (+) HO2S12 Connector, Harness Side (-)
      HO2S12 Ground
    • For HO2S22,
    • Measure the resistance between:
      (+) HO2S22 Connector, Harness Side (-) HO2S22 Connector, Harness Side
      HO2S22 SIGRTN
      HO2S22 VPWR
    • Measure the resistance between:
      (+) HO2S22 Connector, Harness Side (-)
      HO2S22 Ground

    Are the resistances greater than 10K ohms? 

    Yes No
    GO to DW10  . REPAIR the short circuit. Clear the PCM DTCs.
    REPEAT the self-test.
  10. DW10 CHECK THE HO2S CIRCUIT FOR A SHORT TO VOLTAGE 
    • Ignition ON, engine OFF.
    • For HO2S12,
    • Measure the voltage between:
      (+) HO2S12 Connector, Harness Side (-)
      HO2S12 Ground
    • For HO2S22,
    • Measure the voltage between:
      (+) HO2S22 Connector, Harness Side (-)
      HO2S22 Ground

    Is any voltage present? 

    Yes No
    REPAIR the short circuit. Clear the PCM DTCs.
    REPEAT the self-test.    		 GO to DW11  .
  11. DW11 CARRY OUT A THOROUGH WIGGLE TEST ON THE HO2S HARNESS 
    • Ignition OFF.
    • PCM connector connected.
    • For HO2S12,
    • HO2S12 connector connected.
    • Ignition ON, engine OFF.
    • Access the PCM and monitor the O2S12 (VOLT) PID.
    • Carry out a thorough wiggle test on the HO2S12 harness.
    • For HO2S22,
    • HO2S22 connector connected.
    • Ignition ON, engine OFF.
    • Access the PCM and monitor the O2S22 (VOLT) PID.
    • Carry out a thorough wiggle test on the HO2S22 harness.

    Does the voltage change during the wiggle test? 

    Yes No
    REPAIR as necessary.
    Clear the PCM DTCs. REPEAT the self-test.    		 For DTC P00D2, GO to DW12  .
    For all others, INSTALL a new HO2S. REFER to the service information , Electronic Engine Controls.
    CLEAR the DTCs. REPEAT the self-test.
  12. DW12 CHECK FOR VPWR 
    NOTE: Diagnose the suspect sensor indicated by the DTC.
    • Ignition OFF.
    • For HO2S12,
    • HO2S12 connector disconnected.
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      (+) HO2S12 Connector, Harness Side (-)
      VPWR Ground
    • For HO2S22,
    • HO2S22 connector disconnected.
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      (+) HO2S22 Connector, Harness Side (-)
      VPWR Ground

    Is the voltage greater than 10.5 V? 

    Yes No
    GO to DW13  . REPAIR the open circuit. Clear the PCM DTCs.
    REPEAT the self-test.
  13. DW13 CHECK THE HO2S HEATER CIRCUIT FOR AN OPEN 
    • Ignition OFF.
    • PCM connector disconnected.
    • For HO2S12,
    • Measure the resistance between:
      (+) HO2S12 Connector, Harness Side (-) PCM Connector, Harness Side
      HTR12 HTR12
    • For HO2S22,
    • Measure the resistance between:
      (+) HO2S22 Connector, Harness Side (-) PCM Connector, Harness Side
      HTR22 HTR22

    Is the resistance less than 5 ohms? 

    Yes No
    GO to DW14  . REPAIR the open circuit. Clear the PCM DTCs.
    REPEAT the self-test.
  14. DW14 CHECK THE HO2S HEATER FOR SHORT CIRCUITS 
    • For HO2S12,
    • Measure the resistance between:
      (+) HO2S12 Connector, Harness Side (-)
      HTR12 Ground
    • Measure the resistance between:
      (+) HO2S12 Connector, Harness Side (-) HO2S12 Connector, Harness Side
      HTR12 VPWR
      HTR12 SIGRTN
      HTR12 HO2S12
    • For HO2S22,
    • Measure the resistance between:
      (+) HO2S22 Connector, Harness Side (-)
      HTR22 Ground
    • Measure the resistance between:
      (+) HO2S22 Connector, Harness Side (-) HO2S22 Connector, Harness Side
      HTR22 VPWR
      HTR22 SIGRTN
      HTR22 HO2S22

    Are the resistances greater than 10K ohms? 

    Yes No
    GO to DW15  . REPAIR the short circuit. Clear the PCM DTCs.
    REPEAT the self-test.
  15. DW15 CHECK THE INTERNAL RESISTANCE OF THE HO2S HEATER 
    • For HO2S12,
    • Measure the resistance between:
      (+) HO2S12 Connector, Component Side (-) HO2S12 Connector, Component Side
      HTR12 VPWR
    • For HO2S22,
    • Measure the resistance between:
      (+) HO2S22 Connector, Component Side (-) HO2S22 Connector, Component Side
      HTR22 VPWR

    Is the resistance between 2 - 30 ohms? 

    Yes No
    GO to DW16  . INSTALL a new HO2S. REFER to the service information , Electronic Engine Controls. RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
    REPEAT the self-test.
  16. DW16 CHECK THE HEATER CIRCUIT FOR AN INTERNAL SHORT TO GROUND 
    • For HO2S12,
    • Measure the resistance between:
      (+) HO2S12 Connector, Component Side (-) HO2S12 Connector, Component Side
      HTR12 SIGRTN
    • Measure the resistance between:
      (+) HO2S12 Connector, Component Side (-)
      HTR12 Ground
    • For HO2S22,
    • Measure the resistance between:
      (+) HO2S22 Connector, Component Side (-) HO2S22 Connector, Component Side
      HTR22 SIGRTN
    • Measure the resistance between:
      (+) HO2S22 Connector, Component Side (-)
      HTR22 Ground

    Is the resistance greater than 10K ohms? 

    Yes No
    GO to DW17  . INSTALL a new HO2S. REFER to the service information , Electronic Engine Controls.
    RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
    REPEAT the self-test.
  17. DW17 CHECK FOR CORRECT PCM OPERATION 
    • Ignition OFF.
    • Disconnect all the PCM connectors.
    • Visually inspect for:
      • pushed out pins
      • corrosion
    • Connect all the PCM connectors and make sure they seat correctly.
    • Carry out the PCM self-test.
    • Verify the concern is still present.

    Is the concern still present? 

    Yes No
    INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) , Programming the VID Block for a Replacement PCM. The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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