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Test Procedure

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  1. X1 PRELIMINARY DIAGNOSIS FOR DTCS P0470, P0471, P0472, OR P0473 
    NOTE: Diagnose and repair EP sensor circuit fault DTCs before addressing range/performance concerns.
    • Carry out a visual inspection.
    • Retrieve and record all DTCs.
    • Record the freeze frame data.
    • Clear the DTCs.
    • Carry out the key on engine off (KOEO) self-test.
    • Carry out the key on engine running (KOER) self-test.

    Are DTCs P0470, P0471, P0472, or P0473 present? 

    Yes No
    For KOEO DTC P0470, GO to  X2.
    For continuous DTC P0470, GO to  X6.
    For DTC P0471, GO to  X8.
    For DTC P0472, GO to  X12.
    For DTC P0473, GO to  X16.    		 GO to  X19
  2. X2 DIAGNOSTIC TROUBLE CODE (DTC) P0470 
    • Possible causes:
      • EP sensor
      • SIG RTN circuit open or shorted to ground
      • PCM
    • Key ON, engine OFF.
    • Access the EP PID.

    Is the EP PID less than 127 kPa (18.5 psi)? 

    Yes No
    CLEAR the DTCs. REPEAT the KOEO on-demand self-test. If DTC P0470 is present, GO to  X12.
    If no DTCs are present, CHECK for a loose connection, and damaged or corroded terminals. WIGGLE the harness attempting to recreate the fault. REPAIR as necessary. REFER to SYMPTOM CHARTS - 6.0L DIESEL if a driveability concern exists.    		 GO to  X3.
  3. X3 CHECK THE EP SENSOR PRESSURE 

    Is the EP PID value within 10.34 kPa (1.5 psi) of the MAP and BARO PID values? 

    Yes No
    GO to  X5. GO to  X4.
  4. X4 CHECK THE SIGNAL RETURN CIRCUIT 
    • Key OFF.
    • Disconnect the EP sensor.
    • Disconnect the PCM engine connector.
    • Measure the resistance between the EP sensor SIG RTN circuit pin A, harness side and the PCM engine connector pin 25, harness side.

    Is the resistance less than 5 ohms? 

    Yes No
    INSTALL a new EP sensor. CLEAR the DTCs. REPEAT the self-test. REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
  5. X5 CHECK THE EP SENSOR 
    CAUTION: Using air pressure greater than 69 kPa (10 psi) may damage the EP sensor.
    • Remove the EP sensor.
    • Check for contamination, restrictions or carbon build-up in the EP sensor port, mounting bracket or tube. Repair as necessary.
    • Check for moisture in the EP sensor port. If moisture is present, use 69 kPa (10 psi) regulated air pressure to remove the moisture.
    • Connect the EP sensor connector.
    • Connect the PCM connector.
    • Key ON, engine OFF.
    • Access the BARO, EP, and MAP PIDs.
    • Refer to REFERENCE VALUES - EXCURSION (6.0L DIESEL) for normal operating values.

    Is the EP PID value within 10.34 kPa (1.5 psi) of the MAP and BARO PID values? 

    Yes No
    UNABLE to duplicate the condition. CHECK for a loose connection, and damaged or corroded terminals. WIGGLE the harness attempting to recreate the fault. REPAIR as necessary. REFER to SYMPTOM CHARTS - 6.0L DIESEL if driveability concerns exist. INSTALL a new EP sensor. CLEAR the DTCs. REPEAT the self-test.
  6. X6 CONTINUOUS DIAGNOSTIC TROUBLE CODE (DTC) P0470 
    • Possible causes:
      • EP sensor
      • PCM
    • Key ON, engine OFF.
    • Access the EP PID.
    • Observe the EP PID while carrying out the following:
      • Grasp the vehicle harness close to the EP sensor connector.
      • Wiggle and shake the vehicle harness while working toward the PCM.

    Does the EP PID value fluctuate? 

    Yes No
    ISOLATE the intermittent connection. REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test. GO to  X7.
  7. X7 INSPECT THE EP SENSOR AND PCM CONNECTORS 
    • Key OFF.
    • Disconnect the EP sensor.
    • Inspect the EP sensor connector and terminals.
    • Inspect the PCM connectors.

    Are all the connections OK? 

    Yes No
    UNABLE to duplicate the condition. CHECK for a loose connection, and damaged or corroded terminals. WIGGLE the harness attempting to recreate the fault. REPAIR as necessary. REFER to SYMPTOM CHARTS - 6.0L DIESEL if a driveability concern exists. REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.
  8. X8 DIAGNOSTIC TROUBLE CODE (DTC) P0471 
    NOTE: Visually inspect the vehicle for aftermarket accessories and performance modifications (exhaust system, turbocharger, performance chip). Refer to DIESEL ELECTRONIC ENGINE CONTROL (EEC) SYSTEM , MODIFICATIONS TO OBD VEHICLES .
    • Possible causes:
      • EP sensor
      • EP sensor supply tube plugged or restricted
      • PCM
    • Carry out the KOER self-test. If other DTCs are present, repair before continuing. Refer to DIAGNOSTIC TROUBLE CODE (DTC) DESCRIPTIONS .
    • Access the EP PID.
    • Road test the vehicle under hard acceleration while monitoring the EP PID.

    Is the EP increase greater than 25 psi ? 

    Yes No
    UNABLE to duplicate the condition. CHECK for a loose connection, and damaged or corroded terminals. WIGGLE the harness attempting to recreate the fault. REPAIR as necessary. REFER to SYMPTOM CHARTS - 6.0L DIESEL if a driveability concern exists. GO to  X9.
  9. X9 INSPECT FOR EXHAUST LEAKS 
    • Inspect the turbo pipe and exhaust manifolds for leaks.

    Are any exhaust leaks present? 

    Yes No
    REPAIR the exhaust leak. CLEAR the DTCs. REPEAT the self-test. Go to  X10.
  10. X10 CHECK THE EP SENSOR SUPPLY TUBE 
    • Inspect the EP sensor supply tube.

    Is the EP sensor tube restricted or plugged? 

    Yes No
    INSTALL a new EP sensor tube. CLEAR the DTCs. REPEAT the self-test. GO to  X11.
  11. X11 EP SENSOR CHECK 
    • Disconnect the EP sensor.
    • Install the ICP/EBC Adapter Cable D94T-50-A or equivalent between the EP sensor and the vehicle harness.
    • Key ON, engine running.
    • Measure the voltage between the EP signal circuit and ground on the ICP/EBC Adapter Cable D94T- 50-A.
    • Accelerate the engine to wide open throttle (WOT) several times.

    Is the voltage greater than 1.35 volts during acceleration? 

    Yes No
    CLEAR the DTCs. REPEAT the self-test. If DTC P0471 is present again, INSTALL a new PCM. INSTALL a new EP sensor. CLEAR the DTCs. REPEAT the self-test.
  12. X12 DIAGNOSTIC TROUBLE CODE (DTC) P0472 
    • Possible causes:
      • EP sensor signal circuit open
      • biased sensor
      • EP sensor signal circuit shorted to ground
      • VREF circuit open
      • EP sensor
      • PCM
    • Key OFF.
    • Disconnect the EP sensor.
    • Key ON, engine OFF.
    • Measure the voltage between the EP sensor VREF circuit pin B, harness side and ground.

    Is the voltage between 4.5 and 5.5 volts? 

    Yes No
    GO to  X13. REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
  13. X13 CHECK THE EP SENSOR SIGNAL 
    • Access the EP PID.
    • Connect a 5-amp fused jumper wire between the EP sensor VREF circuit pin B, harness side and the EP sensor signal circuit pin C, harness side.

    Is the EP PID voltage approximately 4.5 to 5.5 volts? 

    Yes No
    INSTALL a new EP sensor. CLEAR the DTCs. REPEAT the self-test. GO to  X14.
  14. X14 CHECK THE SIGNAL CIRCUIT FOR AN OPEN 
    • Key OFF.
    • Disconnect the PCM engine connector.
    • Measure the resistance between the EP sensor signal circuit pin C, harness side and the PCM engine connector pin 27, harness side.

    Is the resistance less than 5 ohms? 

    Yes No
    GO to  X15. REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
  15. X15 CHECK THE SIGNAL CIRCUIT FOR A SHORT TO GROUND 
    • Measure the resistance between the EP sensor signal circuit pin C, harness side and ground.

    Is the resistance greater than 10,000 ohms? 

    Yes No
    INSTALL a new PCM. CLEAR the DTCs. REPEAT the self-test. REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
  16. X16 DIAGNOSTIC TROUBLE CODE (DTC) P0473 
    • Possible causes:
      • EP signal shorted to voltage
      • SIG RTN circuit open
      • EP sensor
      • PCM
    • Simulate opposite DTC.
    • Key OFF.
    • Disconnect the EP sensor.
    • Key ON, engine OFF.
    • Carry out the KOEO On-Demand Self-Test.

    Is DTC P0472 present? 

    Yes No
    INSTALL a new EP sensor. CLEAR the DTCs. REPEAT the self-test. GO to  X17.
  17. X17 CHECK THE EP SENSOR SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE 
    • Key OFF.
    • Disconnect the PCM engine harness connector.
    • Key ON, engine OFF.
    • Measure the voltage between the EP sensor signal circuit pin C, harness side and ground.

    Is any voltage indicated? 

    Yes No
    REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. GO to  X18.
  18. X18 CHECK THE EP SENSOR SIGNAL RETURN CIRCUIT FOR AN OPEN 
    • Key OFF.
    • Measure the resistance between the EP sensor SIG RTN circuit pin A, harness side and the PCM engine connector pin 25, harness side.

    Is the resistance less than 5 ohms? 

    Yes No
    INSTALL a new PCM. CLEAR the DTCs. REPEAT the self-test. REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
  19. X19 CHECK THE EP SENSOR FOR BIAS 

    Is the EP PID value within 10.34 kPa (1.5 psi) of the MAP and BARO PID values? 

    Yes No
    CHECK the EP sensor and tube for blockage or restrictions. REPAIR as necessary. REFER to SYMPTOM CHARTS - 6.0L DIESEL if a driveability concern exists. INSTALL a new EP sensor. CLEAR the DTCs. REPEAT the self-test.
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