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Home >> Ford >> 2011 >> Focus S, Standard >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Pinpoint Test A: No Start Through Pinpoint Test DK: Accelerator Pedal Position (App) Sensor - (Except Diesel & Hybrid) >> PINPOINT TEST DC: Mass Airflow (MAF) Sensor >> Test Procedure

Test Procedure

  1. DC1 VERIFY THE TYPE OF MAF SENSOR 

    Does the MAF sensor have 4 pins? 

    Yes No
    GO to  DC15. GO to  DC2.
  2. DC2 CHECK FOR DIAGNOSTIC TROUBLE CODES (DTCS) 
    NOTE: DTC P1101 can be generated by a low charged vehicle battery or the garage exhaust ventilation system. Charge the battery as necessary, then remove the ventilation system and correctly vent to the outside atmosphere.

    Are DTCs P0101, P0102, P0103, P0104, P1100, or P1101 present? 

    Yes No
    For DTCs P0101, P0102, P0103, P0104, P1100 or P1101, GO to  DC3.
    For all others, GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS .    		 For symptoms without DTCs, GO to  DC3.
  3. DC3 CHECK THE INTAKE AIR SYSTEM FOR LEAKS, OBSTRUCTIONS, AND DAMAGE 
    NOTE: Visually inspect the vehicle for aftermarket accessories and performance modifications (exhaust system, turbocharger, performance chip). Refer to ENGINE CONTROL (EC) SYSTEM , Modifications to OBD Vehicles.
    • Ignition OFF.
    • Check the intake air system (air cleaner, housing, ductwork) for obstructions or blockage.
    • Check for broken or loose air outlet tube clamps, cracks or holes in the air outlet tube.
    • Check for worn gaskets between the MAF/IAT sensor and the air cleaner assembly.
    • Check that the MAF/IAT sensor connector is seated correctly.
    • Check the throttle body bore for sludge.
    • Check the crankcase ventilation system for leaks and restrictions.

    Is a concern present? 

    Yes No
    REPAIR as necessary.
    Clear the PCM DTCs. REPEAT the self-test.    		 GO to  DC4.
  4. DC4 CHECK FOR VOLTAGE AT THE SENSOR 
    • MAF/IAT Sensor connector disconnected.
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      VOLTAGE REFERENCE CHART

      (+) MAF/IAT Sensor Connector, Harness Side (-)
      VPWR Ground

    Is the voltage greater than 10 V? 

    Yes No
    GO to  DC5. REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test.
  5. DC5 CHECK FOR AN OPEN IN THE HARNESS 
    NOTE: Only measure the circuits that apply to the vehicle being diagnosed. Refer to the appropriate Wiring Diagram article for the MAF/IAT sensor to determine which circuits to measure.
    • Ignition OFF.
    • MAF/IAT Sensor connector disconnected.
    • PCM connector disconnected.
    • Measure the resistance between:
      RESISTANCE REFERENCE CHART

      (+) MAF/IAT Sensor Connector, Harness Side (-)
      PWRGND Ground
    • Measure the resistance between:
      RESISTANCE REFERENCE CHART

      (+) MAF/IAT Sensor Connector, Harness Side (-) PCM Connector, Harness Side
      MAF MAF
      MAF RTN MAF RTN

    Are the resistances less than 5 ohms? 

    Yes No
    GO to  DC6. REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test.
  6. DC6 CHECK FOR A SHORT BETWEEN CIRCUITS IN THE HARNESS 
    NOTE: Only measure the circuits that apply to the vehicle being diagnosed. Refer to the appropriate Wiring Diagram article for the MAF/IAT sensor to determine which circuits to measure.
    • Measure the resistance between:
      RESISTANCE REFERENCE CHART

      (+) MAF/IAT Sensor Connector, Harness Side (-) MAF/IAT Sensor Connector, Harness Side
      MAF VPWR
      MAF MAF RTN
      MAF SIGRTN
      MAF IAT
    • Measure the resistance between:
      RESISTANCE REFERENCE CHART

      (+) MAF/IAT Sensor Connector, Harness Side (-)
      MAF Ground

    Are the resistances greater than 10K ohms? 

    Yes No
    GO to  DC7. REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test.
  7. DC7 CHECK FOR A SHORT TO VOLTAGE IN THE HARNESS 
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      VOLTAGE REFERENCE CHART

      (+) MAF/IAT Sensor Connector, Harness Side (-)
      MAF Ground

    Is any voltage present? 

    Yes No
    REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test. GO to  DC8.
  8. DC8 INTERMITTENT CHECK 
    • Ignition OFF.
    • PCM connector connected.
    • MAF/IAT Sensor connector connected.
    • Ignition ON, engine running.
    • Run the engine up to 1,500 RPM for 5 seconds, then bring it back to idle. Run the engine up to 1,500 RPM for 5 seconds, then bring it back to idle.
    • If the idle is not stable, refer to NO DIAGNOSTIC TROUBLE CODES (DTCS) PRESENT SYMPTOM CHART INDEX .
    • Access the PCM and monitor the MAF (VOLT) PID.
    • Lightly tap on the MAF/IAT sensor and wiggle the harness connector to simulate road shock.

    Does the MAF PID go below 0.3 volt or above 4.7 volts? 

    Yes No
    INSTALL a new MAF/IAT sensor. REFER to the appropriate Electronic Engine Controls article . RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
    REPEAT the self-test.    		 GO to  DC9.
  9. DC9 CHECK THE INTAKE AIR SYSTEM FOR LEAKS 
    NOTE: Pressure above 241 kPa (35 psi) can cause damage to system components. Regulate the shop air to 137.9 kPa (20 psi) before connecting to the system.
    • Ignition OFF.
    • Connect the Rotunda Smoke Machine, Fuel Evaporative Emission System Tester 218-00001 (522) or equivalent to the intake air system.
    • Fill the intake air system with smoke.
    • Pressurize the intake air system with 137.9 kPa (20 psi) regulated shop air.
    • Check the intake air system for leaks.

    Are any leaks or restrictions present? 

    Yes No
    REPAIR the leaks or restrictions.
    Clear the PCM DTCs. REPEAT the self-test.    		 GO to  DC10.
  10. DC10 CHECK THE MAF PID 
    • Access the PCM and monitor the RPM (RPM) PID.
    • Run the engine up to 1,500 RPM for 5 seconds, then bring it back to idle. Run the engine up to 1,500 RPM for 5 seconds, then bring it back to idle.
    • Access the PCM and monitor the MAF (VOLT) PID.

    Is the voltage less than 0.3 V? 

    Yes No
    INSTALL a new MAF/IAT sensor. REFER to the appropriate Electronic Engine Controls article . RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
    REPEAT the self-test.    		 GO to  DC11.
  11. DC11 CHECK THE MAF CIRCUIT VOLTAGE CYCLING INTEGRITY 
    • Ignition ON, engine OFF.
    • Access the PCM and monitor the MAF (VOLT) PID.
    • Connect a 5 amp fused jumper wire between the following:
      CONNECTOR PINS REFERENCE CHART

      Point A MAF/IAT Sensor Connector, Harness Side Point B
      MAF RTN Ground
    • Connect a 5 amp fused jumper wire between the following:
      CONNECTOR PINS REFERENCE CHART

      Point A MAF/IAT Sensor Connector, Harness Side Point B MAF/IAT Sensor Connector, Harness Side
      MAF VPWR
    • Record the PID reading while both jumpers are installed.
    • Remove the VPWR jumper while observing the MAF V PID.

    Does the MAF PID change from greater than 4.50 volts to less than 0.20 volt when the VPWR jumper is removed? 

    Yes No
    INSTALL a new MAF/IAT sensor. REFER to the appropriate Electronic Engine Controls article . RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
    REPEAT the self-test.    		 GO to  DC12.
  12. DC12 DTCS P0171, P0172, P0174, P0175, P2195, P2196, P2197 OR P2198: CHECK THE FUNCTIONALITY OF THE MAF SENSOR 
    NOTE: A MAF PID value of less than 0.35 volt may indicate an incorrectly installed air cleaner or a leak in the air inlet system.
    • Ignition ON, engine running.
    • Allow the engine to stabilize at the correct operating temperature.
    • Access the PCM and monitor the MAF (VOLT) PID.

    Is the MAF PID at idle and NEUTRAL between 0.35 volt and 1.3 volts? 

    Yes No
    GO to  DC14. GO to  DC13.
  13. DC13 CHECK TO ISOLATE THE MAF SENSOR FROM A LEAN DRIVEABILITY OCCURRENCE 
    NOTE: Due to increasingly stringent emission/OBD requirements, a fuel system DTC on some vehicles can be generated without a noticeable driveability concern with or without the MAF sensor disconnected. Under these conditions, if the MAF PID indicates a MAF sensor concern, install a new MAF sensor. Refer to the appropriate Electronic Engine Controls article .
    • Ignition OFF.
    • MAF/IAT Sensor connector disconnected.
    • Ignition ON, engine running.
    • Drive the vehicle on the road.

    Is the lean driveability symptom (lack of power, spark knock/detonation, buck/jerk or hesitation/surge on acceleration) gone? 

    Yes No
    INSTALL a new MAF/IAT sensor. REFER to the appropriate Electronic Engine Controls article . RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
    REPEAT the self-test.    		 GO to  DC14.
  14. DC14 VERIFY THE DTC 

    Are any of the following DTCs present: P0171, P0172, P0174, P0175, P2195, P2196, P2197, or P2198? 

    Yes No
    GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS . GO to  DC22.
  15. DC15 PRELIMINARY DIAGNOSIS 

    Are DTCs P0102, P0103, P0104 or P1101 present? 

    Yes No
    For DTCs P0102, P0103, P0104 or P1101, GO to  DC16.
    For all others, GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS .    		 For symptoms without DTCs, GO to  DC16.
  16. DC16 CHECK THE INTAKE AIR SYSTEM FOR LEAKS, OBSTRUCTIONS, AND DAMAGE 
    • Ignition OFF.
    • Check the intake air system (air cleaner, housing, ductwork) for obstructions or blockage.
    • Check for broken or loose air outlet tube clamps, cracks or holes in the air outlet tube.
    • Check for worn gaskets between the MAF/IAT sensor and the air cleaner assembly.
    • Check that the MAF/IAT sensor connector is seated correctly.
    • Check the throttle body bore for sludge.
    • Check the crankcase ventilation system for leaks and restrictions.

    Is a concern present? 

    Yes No
    REPAIR as necessary.
    Clear the PCM DTCs. REPEAT the self-test.    		 GO to  DC17.
  17. DC17 CHECK THE VPWR TO THE MAF/IAT SENSOR 
    • MAF/IAT Sensor connector disconnected.
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      VOLTAGE REFERENCE CHART

      (+) MAF/IAT Sensor Connector, Harness Side (-)
      VPWR Ground

    Is the voltage greater than 10 V? 

    Yes No
    GO to  DC18. REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test.
  18. DC18 CHECK THE MAF HARNESS FOR A OPEN 
    • Ignition OFF.
    • MAF/IAT Sensor connector disconnected.
    • PCM connector disconnected.
    • Measure the resistance between:
      RESISTANCE REFERENCE CHART

      (+) MAF/IAT Sensor Connector, Harness Side (-) PCM Connector, Harness Side
      MAF MAF
    • For Motorhome / Stripped Chassis / Step Van.
    • Measure the resistance between:
      RESISTANCE REFERENCE CHART

      (+) MAF/IAT Sensor Connector, Harness Side (-)
      SIGRTN Ground
    • For all others.
    • Measure the resistance between:
      RESISTANCE REFERENCE CHART

      (+) MAF/IAT Sensor Connector, Harness Side (-) PCM Connector, Harness Side
      SIGRTN SIGRTN

    Are the resistances greater than 10K ohms? 

    Yes No
    REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test. GO to  DC19.
  19. DC19 CHECK THE MAF SIGNAL CIRCUIT FOR A SHORT 
    • Measure the resistance between:
      RESISTANCE REFERENCE CHART

      (+) MAF/IAT Sensor Connector, Harness Side (-) MAF/IAT Sensor Connector, Harness Side
      MAF VPWR
      MAF SIGRTN
      MAF IAT
    • Measure the resistance between:
      RESISTANCE REFERENCE CHART

      (+) MAF/IAT Sensor Connector, Harness Side (-)
      MAF Ground

    Are the resistances greater than 10K ohms? 

    Yes No
    GO to  DC20. REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test.
  20. DC20 CHECK FOR AN INTERMITTENT CONCERN 
    • Ignition OFF.
    • PCM connector connected.
    • MAF/IAT Sensor connector connected.
    • Ignition ON, engine running.
    • Run the engine up to 1,500 RPM for 5 seconds, then bring it back to idle. Run the engine up to 1,500 RPM for 5 seconds, then bring it back to idle.
    • If the idle is not stable, refer to NO DIAGNOSTIC TROUBLE CODES (DTCS) PRESENT SYMPTOM CHART INDEX .
    • Access the PCM and monitor the MAF_HZ (FREQ) PID.
    • Lightly tap on the MAF sensor and wiggle the harness connector to simulate road shock.

    Does the MAF PID reading change? 

    Yes No
    INSTALL a new MAF/IAT sensor. REFER to the appropriate Electronic Engine Controls article . RESET the keep alive memory (KAM).
    REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
    REPEAT the self-test.
    If the concern or DTC is still present,
    GO to  DC22.    		 GO to  DC21.
  21. DC21 CHECK THE MAF/IAT HARNESS FOR INTERMITTENT CONCERNS 
    • Access the PCM and monitor the MAF_HZ (FREQ) PID.
    • While observing the PID, wiggle, shake, and bend small sections of the wiring harness working from the sensor to the PCM.

    Does the MAF PID reading change? 

    Yes No
    REPAIR the harness as necessary.
    Clear the PCM DTCs. REPEAT the self-test.    		 INSTALL a new MAF/IAT sensor. REFER to the appropriate Electronic Engine Controls article . RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
    REPEAT the self-test.
    If the concern or DTC is still present,
    GO to  DC22.
  22. DC22 CHECK FOR CORRECT PCM OPERATION 
    • 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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