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HOMESERVICE MANUALSFORD2004PICKUP F350 SUPER DUTY, 4D PICKUP, 6.8 S, RWD, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - PINPOINT TEST DX: ENGINE COOLANT TEMPERATURE (ECT) SENSOR THROUGH PINPOINT TEST HC: FUEL DELIVERY SYSTEM - CNG, FLEX-FUEL & GASOLINEPINPOINT TEST HA: NATURAL GAS FUEL CONTROLTEST PROCEDURE
2004 Ford Pickup F350 Super Duty, 4D Pickup, 6.8 S, RWD, Automatic

Test Procedure

2004 Ford Pickup F350 Super Duty, 4D Pickup, 6.8 S, RWD, AutomaticSECTION Test Procedure
NOTE: Proceed to DTC testing steps listed in FAULT CODE SETTING CONDITION  table of fault code setting condition.
FAULT CODE SETTING CONDITION

Fault Code KOEO KOER Continuous Memory
P0040  HA52  HA52  HA52
P0041  HA52  HA52  HA52
P0135  HA1  HA1  HA1
P0141  HA1  HA1  HA1
P0155  HA1  HA1  HA1
P0161  HA1  HA1  HA1
P0171  HA10  HA10  HA10
P0172  HA10  HA10  HA10
P0174  HA10  HA10  HA10
P0175  HA10  HA10  HA10
P0201  HA27  HA27  HA27
P0202  HA27  HA27  HA27
P0203  HA27  HA27  HA27
P0204  HA27  HA27  HA27
P0205  HA27  HA27  HA27
P0206  HA27  HA27  HA27
P0207  HA27  HA27  HA27
P0208  HA27  HA27  HA27
P0209  HA27  HA27  HA27
P0210  HA27  HA27  HA27
P0211  HA27  HA27  HA27
P0212  HA27  HA27  HA27
P1127    HA49  
P1128    HA50  
P1129  HA52  HA52  HA52
P1130      HA9
P1131  HA9  HA9  HA9
P1132  HA9  HA9  HA9
P1261      HA27
P1262      HA27
P1263      HA27
P1264      HA27
P1265      HA27
P1266      HA27
P1267      HA27
P1268      HA27
P1271      HA27
P1272      HA27
P1273      HA27
P1274      HA27
P1275      HA27
P1276      HA27
P1277      HA27
P1278      HA27
P2195    HA9  HA9
P2196  HA9  HA9  HA9
P2197  HA50  HA50  HA50
P2198  HA9  HA9  HA9
P2278  HA52  HA52  HA52
  1. HA1 DTCS P0135, P0141, P0155 AND P0161: HO2S HTR CIRCUIT FAULT 
    • DTC/HO2S reference list:
      • DTC P0135 = HO2S HTR-11.
      • DTC P0141 = HO2S HTR-12.
      • DTC P0155 = HO2S HTR-21.
      • DTC P0161 = HO2S HTR-22.
      NOTE: On some applications, a vehicle hoist is required to access the HO2S harness.
    • Visually inspect the HO2S harness for exposed wiring, water contamination, corrosion, and proper assembly.

    Were any of the above conditions or concerns found during inspection? 

    Yes No
    Repair any concerns found. GO to  HA2.
  2. HA2 PERFORM THE KOEO SELF-TEST 
    • Key ON Engine RUN.
    • Engine at 2,000 RPM for 1 minute.
    • Key ON Engine OFF.
    • Run PCM KOEO Self-Test.

    Are DTCs P0135, P0141, P0155 or P0161 present? 

    Yes No
    KEY OFF.
    GO to  HA3.    		 KEY OFF.
    Unable to duplicate or identify the fault at this time.
    GO to PINPOINT TEST Z step 1 .
  3. HA3 CHECK THE VPWR VOLTAGE TO HO2S HARNESS CONNECTOR 
    NOTE: If DTCs P0135 and P0155 or P0141 and P0161 are displayed, both heater circuits require testing. DTCs displayed separately are tested individually.
    • HO2S connector disconnected.
    • Key ON Engine OFF.
    • Measure the voltage between:
    ( + )HO2S Connector, Harness Side  ( - )HO2S Connector, Harness Side 
    VPWR SIGRTN

    Is the voltage greater than 10.5 V? 

    Yes No
    KEY OFF.
    GO to  HA5.    		 KEY OFF.
    GO to  HA4.
  4. HA4 CHECK THE VPWR CIRCUIT FOR AN OPEN IN THE HARNESS 
    • PCM connector disconnected.
    • Measure the resistance between:
    ( + )PCM Connector, Harness Side  ( - )HO2S Connector, Harness Side 
    VPWR - Pin 71 VPWR

    Is the resistance less than 5 ohms? 

    Yes No
    GO to  HA5. REPAIR open circuit.
    CHECK the fuse.
  5. HA5 CHECK HO2S HEATER RESISTANCE 
    • HO2S connector disconnected.
    • Measure the resistance between:
    ( + )HO2S Connector, Component Side  ( - )HO2S Connector, Component Side 
    HO2S Heater VPWR

    Is the resistance between 3 ohms - 30 ohms? 

    Yes No
    GO to  HA6. INSTALL a new HO2S.
  6. HA6 CHECK THE HO2S CASE FOR A SHORT TO VPWR AND SIGRTN 
    • Measure the resistance between:
    ( + )HO2S Connector, Component Side  ( - )HO2S Connector, Component Side 
    SIGRTN HO2S Case
    VPWR HO2S Case

    Are the resistances greater than 10K ohms? 

    Yes No
    GO to  HA7. INSTALL a new HO2S.
  7. HA7 CHECK THE HO2S HEATER CIRCUIT FOR SHORTS TO VPWR AND GROUND 
    • PCM connector disconnected.
    • Measure the resistance between:
      ( + )HO2S Connector, Harness Side  ( - )HO2S Connector, Harness Side 
      HO2S Heater HO2S Signal
      HO2S Heater VPWR
      HO2S Heater SIGRTN
    • Measure the resistance between:
    ( + )HO2S Connector, Harness Side  ( - )Vehicle battery 
    HO2S Heater Negative terminal

    Is the resistance greater than 10K ohms? 

    Yes No
    GO to  HA8. REPAIR short circuit.
  8. HA8 CHECK THE HO2S HEATER GROUND FOR AN OPEN IN THE HARNESS 
    • Measure the resistance between:
    ( + )PCM Connector, Harness Side  ( - )HO2S Connector, Component Side 
    HO2S Heater HO2S Heater

    Is the resistance less than 5 ohms? 

    Yes No
    INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASEABLE PROGRAMMABLE READ ONLY MEMORY - FLASH EEPROM . REPAIR open circuit.
  9. HA9 DTCS P1130, P1131, P1132, P1150, P1151, P1152, P2195, P2196, P2197 AND P2198: UPSTREAM HO2S (S) NOT SWITCHING 
    • DTC/HO2S reference list:
      • HO2S-11 = DTCs P1131, P1132, P1130, P2195 and P2196.
      • HO2S-21 = DTCs P1151, P1152, P1150, P2197 and P2198.
    • CHECK the intake air system for leaks, obstructions and damage.
    • Verify the integrity of the PCV system.
    • CHECK for disconnected spark plug wires.
    • Check for vacuum leaks.

    Are any of the above concerns present? 

    Yes No
    Repair as necessary. GO to PINPOINT TEST DC step 25 .
  10. HA10 DTCS P0171, P0172, P0174 AND P0175: FUEL SYSTEM AT THE CORRECTED FUEL TRIM 
    • Fuel system DTC reference list:
      • Bank 1 = DTCs P0171 (lean) and P0172 (rich).
      • Bank 2 = DTCs P0174 (lean) and P0175 (rich).
    • CHECK the intake air system for leaks, obstructions and damage.
    • Check the air cleaner for blockage.
    • Verify the customer did not run out of fuel.
    • Verify clean sufficient fuel.
    • Verify the integrity of the PCV system.
    • CHECK for disconnected spark plug wires.
    • Check for vacuum leaks.

    Are any of the above concerns present? 

    Yes No
    REPAIR as necessary. GO to PINPOINT TEST DC step 25 .
  11. HA11 RETRIEVE THE CONTINUOUS MEMORY DTCS 
    • Retrieve Continuous Memory DTCs

    Are DTCs P1130, P1150, P0171, P0174, P0172 or P0175 present? 

    Yes No
    KEY OFF.
    GO to  HA12.    		 GO to PINPOINT TEST Z step 1 .
  12. HA12 PERFORM THE KOER SELF-TEST 
    • Run KOER Self-Test.

    Are DTCs P1131, P1132, P1151, P1152, P2195, P2196, P2197 or P2198 present? 

    Yes No
    KEY OFF.
    GO to  HA13.    		 GO to PINPOINT TEST Z step 1 .
  13. HA13 CHECK THE FUEL PRESSURE 
    NOTE: THE FUEL SYSTEM IS PRESSURIZED WHEN THE ENGINE IS NOT RUNNING. TO PREVENT INJURY OR FIRE, USE CAUTION WHEN WORKING ON THE FUEL SYSTEM. BECOME FAMILIAR WITH THE WARNING, CAUTION AND NOTE IN PINPOINT TEST HB BEFORE SERVICING.
    • Key ON Engine OFF.
    • Access the PCM -FRP PID.
    • Record the fuel pressure.
    • Increase engine speed to 2,500 RPM and maintain the speed for 1 minute. Record the pressure reading.

    Is the pressure between 552 kPa (80.1 psi) - 827 kPa (119.9 psi)? 

    Yes No
    KEY OFF.
    GO to  HA14.    		 GO to  HB1.
  14. HA14 CHECK THE FUEL SYSTEM FOR PRESSURE STABILITY 
    • Cycle the key ON and OFF twice.
    • Key ON Engine OFF.
    • Access the PCM -FRP PID.
    • Monitor the fuel pressure for 2 minutes.
    • INSPECT the fuel system for external leaks.

    Does the fuel pressure remain within 69 kPa (10 psi) of the highest reading after 2 minutes? 

    Yes No
    For No Start symptom  GO to  HA15.
    For DTCs P1130, P1150, P0171, P0172, P0174 and P0175: 
    GO to  HA15.
    For all other symptoms: 
    GO to  HA32.    		 GO to  HB1.
  15. HA15 CHECK THE FUEL SYSTEM FOR PRESSURE STABILITY WITH KEY ON 
    • Key ON Engine OFF.
    • Access the FRP PID and monitor the fuel pressure.

    Does the fuel pressure remain within 69 kPa (10 psi) of the highest reading after 10 seconds? 

    Yes No
    For No Start symptom  GO to  HA16.

    For DTCs P1130, P1150, P0171 and P0174: 


    GO to  HA25.    		 REPAIR the pressure concern.
    GO to  HA26.
  16. HA16 CHECK THE FUEL INJECTORS ABILITY TO DELIVER FUEL 
    • Access the PCM -FRP PID.
    • Access the FRP PID and monitor the fuel pressure.
    • Cycle the key ON and OFF twice.
    • IFS connector disconnected.
    • Crank the engine for 10 seconds and monitor the fuel pressure reading.

    Was there a pressure drop greater than 34 kPa (10 psi)? 

    Yes No
    Concern is elsewhere. RETURN to SYMPTOM CHARTS - CNG, FLEX-FUEL & GASOLINE for further direction. GO to  HA17.
  17. HA17 CHECK THE VREF VOLTAGE AT THE NATURAL GAS (NG) VEHICLE MODULE 
    • IFS connector connected.
    • INSTALL an NG module breakout box.
    • Key ON Engine OFF.
    • Measure the voltage between:
    ( + )NG Module connector  ( - )NG Module connector 
    SRef SRtn

    Is the voltage between 4 V - 6 V? 

    Yes No
    KEY OFF.
    For No Start symptom 
    GO to  HA18.
    For all other symptoms: 
    GO to  HA27.    		 KEY OFF.
    GO to  HA20.
  18. HA18 CHECK FOR AN OPEN IN POWER GROUND 
    • NG Module connector disconnected.
    • Measure the resistance between:
    ( + )NG Module Connector, Harness Side  ( - )Vehicle battery 
    PWRGND Negative terminal

    Is the resistance less than 5 ohms? 

    Yes No
    GO to  HA19. REPAIR open circuit.
  19. HA19 CHECK FOR AN OPEN IN THE POWER GROUND CIRCUIT IN THE NG MODULE 
    • NG Module connector disconnected.
    • Measure the resistance between:
    ( + )NG Module Connector, Harness Side  ( - )NG Module Connector, Harness Side 
    PWRGND SRtn

    Is the resistance less than 5 ohms? 

    Yes No
    For No Start symptom
    GO to  HA27.
    For all other symptoms:
    GO to PINPOINT TEST A step 9 .    		 INSTALL a new NG module.
  20. HA20 CHECK VREF VOLTAGE 

    Is the VREF reading greater than 6 volts? 

    Yes No
    GO to  HA25. GO to  HA21.
  21. HA21 CHECK BATTERY VOLTAGE 
    • Measure the battery voltage across the terminals.

    Is the voltage reading greater than 10.5 volts? 

    Yes No
    GO to  HA22. REFER to the appropriate GENERATORS & REGULATORS article.
  22. HA22 CHECK VPWR AT THE NG MODULE 
    • Key ON Engine OFF.
    • Measure the voltage between:
    ( + )NG Module Connector, Harness Side  ( - )NG Module Connector, Harness Side 
    VPWR PWRGND

    Is the voltage greater than 10.5 V? 

    Yes No
    GO to  HA24. GO to  HA23.
  23. HA23 CHECK THE VOLTAGE BETWEEN THE VPWR AT THE NG MODULE AND BATTERY GROUND 
    • Measure the voltage between:
    ( + )NG Module Connector, Harness Side  ( - )Vehicle battery 
    VPWR Negative terminal

    Is the voltage greater than 10.5 V? 

    Yes No
    REPAIR open circuit.
    (Ground)    		 REPAIR open circuit.
    (Power)
  24. HA24 CHECK THE VREF VOLTAGE TO THE FUEL TANK PRESSURE SENSOR 
    • FTP Sensor connector disconnected. (On the Crown Victoria the fuel tank pressure sensor is located under the vent box cover of the upper tank assembly.)
    • Key ON Engine OFF.
    • Measure the voltage between:
    ( + )FTP Sensor Connector, Harness Side  ( - )FTP Sensor Connector, Harness Side 
    VREF SIGRTN

    Is the voltage between 4 V - 6 V? 

    Yes No
    KEY OFF. INSTALL a new FTP sensor.
    REFER to the appropriate FUEL SYSTEM article.    		 KEY OFF.
    GO to  HA26.
  25. HA25 CHECK THE VREF CIRCUIT FOR A SHORT TO POWER IN THE HARNESS 
    • FTP Sensor connector disconnected.
    • NG Module connector disconnected.
    • Key ON Engine OFF.
    • Measure the voltage between:
    ( + )NG Module Connector, Harness Side  ( - )NG Module Connector, Harness Side 
    SRef PWRGND

    Is the voltage less than 1 V? 

    Yes No
    INSTALL a new NG module. REPAIR short circuit to PWR.
  26. HA26 CHECK THE VREF CIRCUIT FOR A SHORT TO POWER GROUND 
    • NG Module connector disconnected.
    • Measure the resistance between:
    ( + )NG Module Connector, Harness Side  ( - )NG Module Connector, Harness Side 
    SRef SRtn
    SRef PWRGND
    SRef CASE GND

    Are the resistances greater than 10K ohms? 

    Yes No
    INSTALL a new NG module. REPAIR short circuit to GND.
  27. HA27 CHECK THE FUEL INJECTOR(S) AND HARNESS RESISTANCE FROM THE NATURAL GAS (NG) MODULE TO THE FUEL INJECTOR(S) 
    NOTE: If diagnosing DTC(s) P0201 - P0212, only check the resistance of the suspect fuel injector(s).
    • NG Module connector disconnected.
    • Measure the resistance between:
    ( + )NG Module Connector, Harness Side  ( - )NG Module Connector, Harness Side 
    VPWR INJ1 Out
    VPWR INJ2 Out
    VPWR INJ3 Out
    VPWR INJ4 Out
    VPWR INJ5 Out
    VPWR INJ6 Out
    VPWR INJ7 Out
    VPWR INJ8 Out

    Are the resistances between 3 ohms - 7 ohms? 

    Yes No
    GO to  HA30. GO to  HA28.
  28. HA28 CHECK THE FUEL INJECTOR(S) HARNESS RESISTANCE BETWEEN THE NG MODULE AND THE FUEL INJECTOR 
    • INJ connector disconnected.
    • Measure the resistance of injector circuits between the NG module harness connector pins and the fuel injector(s) harness connector.
    • Measure the resistance between:
    ( + )NG Module Connector, Harness Side  ( - )INJ Connector, Harness Side 
    INJ1 Out INJ
    INJ2 Out INJ
    INJ3 Out INJ
    INJ4 Out INJ
    INJ5 Out INJ
    INJ6 Out INJ
    INJ7 Out INJ
    INJ8 Out INJ
    VPWR VPWR

    Are the resistances less than 5 ohms? 

    Yes No
    GO to  HA29. REPAIR open circuit.
  29. HA29 CHECK THE FUEL INJECTOR HARNESS CIRCUIT FOR SHORTS TO POWER AND GROUND BETWEEN THE NG MODULE AND INJECTORS 
    • Measure the resistance between:
    ( + )NG Module Connector, Harness Side ( - )NG Module Connector, Harness Side
    INJ1 Out VPWR
    INJ2 Out VPWR
    INJ3 Out VPWR
    INJ4 Out VPWR
    INJ5 Out VPWR
    INJ6 Out VPWR
    INJ7 Out VPWR
    INJ8 Out VPWR
    INJ1 Out PWRGND
    INJ2 Out PWRGND
    INJ3 Out PWRGND
    INJ4 Out PWRGND
    INJ5 Out PWRGND
    INJ6 Out PWRGND
    INJ7 Out PWRGND
    INJ8 Out PWRGND

    Are the resistances greater than 10K ohms? 

    Yes No
    For other than P0172 and P0175, REPLACE only the damaged fuel injector(s). Otherwise:
    GO to  HA31.    		 REPAIR short circuit.
  30. HA30 CHECK THE FUEL INJECTOR DRIVER SIGNAL 
    • NG Module connector connected.
    • This test step requires a standard 12-volt test lamp.
      NOTE: A properly operating system shows a dim glow at idle on the test lamp.
    • Connect non-powered test lamp between:
      ( + )Fuel Injector Connector, Harness Side  ( - )Fuel Injector Connector, Harness Side 
      INJ VPWR
    • Crank or start the engine.

    Does the test lamp have a dim glow while cranking or running the engine? 

    Yes No
    Runs Rough condition, RETURN to SYMPTOM CHARTS - CNG, FLEX-FUEL & GASOLINE .

    For No Start symptom 


    GO to A5 .

    For all other symptoms: 


    GO to  HA34.    		 No light/bright continuous light:
    GO to  HA31.
  31. HA31 CHECK THE PCM FUEL INJECTOR HARNESS CIRCUIT RESISTANCE 
    • PCM connector disconnected.
    • NG Module connector disconnected.
    • Measure the resistance between:
    ( + )PCM Connector, Harness Side  ( - )NG Module Connector, Harness Side 
    VPWR - Pin 71 VPWR
    INJ1 - Pin 75 INJ1
    INJ2 - Pin 101 INJ2
    INJ3 - Pin 74 INJ3
    INJ4 - Pin 100 INJ4
    INJ5 - Pin 73 INJ5
    INJ6 - Pin 99 INJ6
    INJ7 - Pin 72 INJ7
    INJ8 - Pin 98 INJ8

    Are the resistances less than 5 ohms? 

    Yes No
    GO to  HA32. REPAIR open circuit.
  32. HA32 CHECK THE PCM FUEL INJECTOR CIRCUIT FOR SHORT TO POWER AND GROUND IN THE HARNESS 
    • Measure the resistance between:
    ( + )NG Module Connector, Harness Side  ( - )NG Module Connector, Harness Side 
    INJ1 VPWR
    INJ2 VPWR
    INJ3 VPWR
    INJ4 VPWR
    INJ5 VPWR
    INJ6 VPWR
    INJ7 VPWR
    INJ8 VPWR
    INJ1 PWRGND
    INJ2 PWRGND
    INJ3 PWRGND
    INJ4 PWRGND
    INJ5 PWRGND
    INJ6 PWRGND
    INJ7 PWRGND
    INJ8 PWRGND

    Are the resistances greater than 10K ohms? 

    Yes No
    For other than P0172 and P0175, REPLACE only the damaged fuel injector(s). Otherwise:
    GO to  HA33.    		 REPAIR short circuit.
  33. HA33 CHECK THE FUEL INJECTOR DRIVER SIGNAL FROM THE PCM 
    • This test requires a standard 12-volt test lamp.
    • PCM connector connected.
    • NG Module connector connected.
      NOTE: A properly operating system shows a dim glow or flicker at idle on the test lamp.
    • Connect a test lamp between the VPWR circuit and each PCM Fuel Injector signal circuit at the NG module harness connector.

    Does the test lamp have a dim glow or flicker while cranking or starting the engine? 

    Yes No
    For no starts: REPLACE the NG module. For runs rough: RETURN to the Symptom Chart. For DTCs:
    GO to  HA34.    		 INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASEABLE PROGRAMMABLE READ ONLY MEMORY - FLASH EEPROM .
  34. HA34 FLOW TEST THE FUEL INJECTORS 
    • Use the Rotunda Natural Gas (NG) Injector Tester found in the special NG Tool Kit (113-00114) or equivalent to flow test the NG fuel injectors. Follow the Rotunda Natural Gas (NG) Injector Tester test steps indicated below, or follow the specific instructions included with the injector tester you are using.
    • Observe the WARNINGS, CAUTIONS, and NOTES.
    • Key OFF.
    • Key ON Engine OFF.
    • Access the PCM -FPM PID.
    • Note the initial FRP sensor pressure using the scan tool.
    • Electronic fuel injector tester installed to suspect fuel injector.
    • Select a pulse width of 200 msec.
    • Activate the fuel injector tester.
    • Note the final FRP sensor pressure using the scan tool.
    • Subtract the final pressure from the initial pressure to determine the pressure drop.
    • REPEAT the above test procedure for all remaining fuel injectors.

    Are the leakage and flow within specifications? 

    Yes No
    For P0171, P0172, P0174, P0175: 
    GO to PINPOINT TEST Z step 1 .
    For P1130 and P1150: 
    GO to  HA37.
    For misfire related DTCs: 
    GO to PINPOINT TEST HD step 8 .
    For all other symptoms: 
    GO to  HA36.    		 INSTALL a new Fuel Injector.
  35. HA35 CYLINDER COMPRESSION CHECK 
    • REFER to the appropriate ENGINE article.

    Are the cylinder compression readings within specification? 

    Yes No
    For DTCs P1132, P1152, P2196 and P2198: 
    GO to  HA41.
    For all other symptoms: 
    GO to  HA36.    		 REPAIR as necessary.
  36. HA36 CHECK HO2S INTEGRITY 
    • CHECK the HO2S harness for chafing, or damage. REPAIR as required.
    • Visually inspect the HO2S and connector for indication of submersion in water, oil and coolant.
    • REPAIR as necessary.
    • Run the engine at 2,000 RPM for 2 minutes.
    • Perform the KOER self-test.
    • Key OFF.

    Are DTCs P1131, P1151, P2195 and/or P2197 present? 

    Yes No
    GO to  HA37. Unable to duplicate or identify the fault.
    GO to PINPOINT TEST Z step 1 .
  37. HA37 CHECK THE HO2S'S ABILITY TO GENERATE A VOLTAGE GREATER THAN 0.5 VOLT 
    • Any vacuum or air leaks can cause DTCs P1131, P1151, P1130, P1150, P2195 and P2197.
    • HO2S connector disconnected.
    • Connect the digital multimeter to the HO2S signal circuit and HO2S SIG RTN circuit or HO2S GND circuit at the HO2S sensor connector.
    • Run the engine at 2,000 RPM for 2 minutes.
    • Rerun the KOER self-test and monitor the HO2S voltage.

    Does the voltage reading indicate greater than 0.5 volt during or at the end of the self-test? 

    Yes No
    GO to  HA38. INSTALL a new HO2S.
  38. HA38 CHECK THE HO2S SIGNAL AND THE HO2S GROUND CIRCUITS FOR AN OPEN IN THE HARNESS 
    • PCM connector disconnected.
    • HO2S connector disconnected.
    • Measure the resistance between:
    ( + )PCM Connector, Harness Side  ( - )HO2S Connector, Harness Side 
    HO2S Signal HO2S Signal
    SIGRTN - Pin 91 SIGRTN

    Are the resistances less than 5 ohms? 

    Yes No
    GO to  HA39. REPAIR open circuit.
  39. HA39 CHECK THE HO2S CIRCUIT FOR A SHORT TO GROUND IN THE HARNESS 
    • Measure the resistance between:
    ( + )PCM Connector, Harness Side  ( - )Vehicle battery 
    HO2S Signal Negative terminal

    Is the resistance greater than 10K ohms? 

    Yes No
    GO to  HA40. REPAIR short circuit.
  40. HA40 CHECK THE HO2S CIRCUIT FOR A SHORT TO GROUND 
    • Measure the resistance between:
    ( + )HO2S Connector, Harness Side  ( - )PCM Connector, Harness Side 
    HO2S Signal PWRGND - Pin 103
    HO2S Signal SIGRTN - Pin 91

    Are the resistances greater than 10K ohms? 

    Yes No
    For other than P1130 and P1150, INSTALL a new PCM. Otherwise:
    GO to  HA41.    		 REPAIR short circuit.
  41. HA41 CHECK FOR DTCS P1132, P1152, P2196 AND P2198 WITH P1130 AND P1150 
    • Perform the KOER self-test.

    Are DTCs P1132, P1152, P2196 or P2198 present? 

    Yes No
    GO to  HA42. Unable to duplicate or identify the fault at this time.
    GO to PINPOINT TEST Z step 1 .
  42. HA42 CHECK THE HO2S SIGNAL FOR A SHORT TO VPWR AND VREF 
    • DTCs P1130, P1132, P2196=HO2S -11.
    • DTCs P1150, P1152, P2198=HO2S -21.
    • Key ON Engine OFF.
    • Access the HO2S PID for the DTC generated.

    Is the voltage greater than 1 volt and less than 4 volts? 

    Yes No
    GO to  HA43. GO to  HA45.
  43. HA43 CHECK THE HO2S CIRCUIT FOR A SHORT TO VPWR 
    • Key OFF.
    • HO2S connector disconnected.
    • PCM connector disconnected.
    • Measure the resistance between:
    ( + )HO2S Connector, Harness Side  ( - )HO2S Connector, Harness Side 
    HO2S Signal VPWR

    Is the resistance greater than 10K ohms? 

    Yes No
    GO to  HA44. REPAIR short circuit to PWR.
  44. HA44 CHECK THE HO2S CIRCUIT FOR A SHORT TO POWER IN THE CONTROL MODULE 
    • PCM connector connected.
    • HO2S connector disconnected.
    • Key ON Engine OFF.
    • Access the PCM -HO2S Signal PID.

    Is the HO2S voltage less than 0.2 volt? 

    Yes No
    INSTALL a new HO2S. INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASEABLE PROGRAMMABLE READ ONLY MEMORY - FLASH EEPROM .
  45. HA45 ATTEMPT TO GENERATE DTCS P1131, P1151, P2195 AND P2197 
    • HO2S connector disconnected.
    • Connect a 5 amp fused jumper wire between the following:
      Point A HO2S Connector, Harness Side  Point B Vehicle battery 
      HO2S Signal Negative terminal
    • Activate the KOER self-test.

    Is DTC P1131, P1151, P2195 or P2197 present? 

    Yes No
    GO to  HA46. Disconnect the PCM and inspect the connector for damage. If OK
    REPLACE the PCM. REFER to FLASH ELECTRICALLY ERASEABLE PROGRAMMABLE READ ONLY MEMORY - FLASH EEPROM .
  46. HA46 HO2S SENSOR VOLTAGE CHECK 
    • HO2S connector disconnected.
    • Connect the digital multimeter to the HO2S SIG circuit and HO2S SIG RTN circuit at the HO2S sensor connector.
    • Disconnect the vacuum hose from the vacuum tree.
    • Start the engine and run at 2,000 RPM.

    Does the voltage reading indicate less than 0.4 volt within 30 seconds? 

    Yes No
    GO to  HA47. INSTALL a new HO2S.
  47. HA47 MONITOR THE HO2S PID FOR PROPER SWITCHING 
    • Key ON Engine RUN.
    • Engine at operating temperature.
    • Access the PCM -HO2S Signal PID.
    • Perform a wiggle test on the harness connected to the HO2S sensor.

    Did the HO2S voltage stay high (greater than 0.45 volt ) or low (less than 0.45 volt)? 

    Yes No
    Isolate the cause of lack of HO2S switching and repair. GO to  HA48.
  48. HA48 TEST DRIVE WHILE MONITORING THE HO2S PID FOR PROPER SWITCHING 
    NOTE: This test step requires an observer to monitor the PID for proper operation.
    • Access the PCM -HO2S Signal PID.
    • While an observer views the HO2S PID, test drive vehicle under different road conditions in an attempt to simulate the original fault.

    Does the HO2S appear to switch properly? 

    Yes No
    Unable to duplicate or identify the fault at this time. INSTALL a new HO2S.
  49. HA49 DTC P1127 KOER 
    • Possible causes:
      • Engine not operating long enough prior to performing KOER self-test.
      • Exhaust system too cool.
    • Key ON Engine RUN.
    • Access the PCM -HTR11 and PCM-HTR21 PIDs.
    • Access HTR11, 21 PIDs.

    Do all PIDs indicate on? 

    Yes No
    With the engine still running, carry out a KOER self-test to verify P1127 is no longer present. Operate the engine until all PIDs indicate ON. Carry out a KOER self-test.
  50. HA50 DTC P1128 KOER 
    • P1128 refers to the upstream HO2S. Possible causes:
      • Crossed HO2S harness connectors.
      • Crossed wiring at the PCM 104-pin harness connector.
    • Key OFF.
    • Visually inspect the HO2S connector(s) for any crossed or stretched wire, or wire harnesses that are not mounted properly.

    Are there any indications of crossed connectors or wires? 

    Yes No
    Repair as necessary. GO to  HA51.
  51. HA51 VERIFY PROPER HO2S SIGNAL PIN LOCATION 
    • PCM connector disconnected.
    • Disconnect both of the suspect HO2S sensors at the HO2S harness connector.
    • P1128 = HO2S 11/21 Upstream.
      • HO2S-11 = Test Pin 60.
      • HO2S-21 = Test Pin 87.
    • Measure the resistance between:
    ( + )HO2S Connector, Harness Side  ( - )PCM Connector, Harness Side 
    HO2S Signal HO2S Signal

    Is the resistance less than 5 ohms? 

    Yes No
    HO2S SIG circuit is OK.
    Unable to duplicate or identify the fault at this time.    		 CONNECT the HO2S connector to the proper HO2S or RELOCATE the HO2S signal pins in the PCM harness connector or HO2S harness connector.
  52. HA52 KOER DTCS P0040, P0041, P1129 AND P2278: CROSSED SENSOR WIRES 
    • Key OFF.
      NOTE: Sensor wiring swapped bank to bank.
    • WARNING: Use caution near hot components.
    • Confirm the wiring is connected to the opposite bank.

    Are there any crossed connections or wires? 

    Yes No
    Swap the connectors on the H02S sensors
    CLEAR the DTCs and REPEAT Self-Test.    		 KEY OFF.
    Unable to duplicate or identify the fault at this time.
    GO to PINPOINT TEST Z step 1 .
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.