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Test Dc: Mass Airflow Sensor: Testing

WARNING: This page does not describe the selected car, but rather 25 other vehicles, including the 2002 Lincoln Town Car, 2002 Lincoln Navigator, 2002 Lincoln LS, 2002 Lincoln Continental, and 2002 Lincoln Blackwood. However, it is still accessible from the selected car via links, so may be relevant.
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
P0102    DC2  DC2
P0103  DC20  DC20  DC20
P1100      DC16
P1101  DC3  DC1  
    NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  1. 1) KOER DTC P1101: Check For MAF Sensor Continuous Memory DTCs
    DTC P1101, retrieved during KOER on-demand self-test, indicates MAF sensor voltage signal was not 0.46-2.44 volts during KOER on-demand self-test. Possible causes for this fault are:
    • Low Battery Charge
    • Contaminated Or Faulty MAF Sensor Or Connector
    • Open In PWR GND Circuit To MAF Sensor
    • Open In MAF RTN Circuit To MAF Sensor
    • Faulty PCM

    Drive vehicle for 6-10 minutes and repeat KOER ON-DEMAND SELF-TEST , KOEO ON-DEMAND SELF-TEST and CONTINUOUS MEMORY SELF-TEST . If no Continuous Memory DTCs are present with KOER DTC P1101, turn ignition switch to OFF position and go to step  3). If any Continuous Memory DTCs are present with KOER DTC P1101, proceed as follows:

    • For Continuous Memory DTC P0102, go to next step.
    • For Continuous Memory DTC P0103, go to step  20).
    • All other Continuous Memory DTCs, service DTCs as necessary. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .

    2. NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  2. 2) KOER & Continuous Memory DTC P0102: Check MAF Sensor Signal Low Input To PCM
    DTC P0102 indicates MAF signal (voltage) fell below the minimum calibrated limit during KOEO or KOER Comprehensive Component Monitor (CCM). Possible causes for this fault are:
    • MAF Sensor Disconnected
    • MAF Circuit Open To PCM
    • VPWR Circuit Open To MAF Sensor
    • MAF RTN Circuit Open To PCM
    • MAF Circuit Shorted To Ground
    • Intake Air Leak (Near MAF Sensor)
    • Closed Throttle Indication
    • Faulty MAF Sensor Or Connector
    • Faulty PCM

    Check for broken or loose air outlet tube clamps at throttle body and air cleaner assembly. Check for holes and cracks in air outlet tube. Check for worn gaskets between MAF sensor and air cleaner. Repair as necessary. Start engine and allow to idle. Check for KOER DTCs. If KOER DTC P0505 is present, go to TEST KE, step 2) . On A/T models, if engine stalls or cannot maintain idle speed, go to step  7). If KOER DTC P0505 is not present and engine idles okay, raise engine speed to 1500 RPM for 5 seconds, then allow to return to idle. Using scan tool, access MAF V PID from PID/DATA MONITOR & RECORD menu. If MAF V PID voltage is less than .23 volt, go to step  4). If MAF V PID voltage is .23 volt or more, go to next step.

    3. NOTE: DTC P1101 may be caused by low battery voltage or by a poorly ventilated work area. Ensure vehicle is vented to outside atmosphere before repeating QUICK TEST .

  3. 3) KOEO DTC P1101: Check For MAF Sensor Signal Out Of Self-Test Range
    DTC P1101, retrieved during KOEO on-demand self-test, indicates MAF sensor voltage signal was more than 0.27 volts during KOEO on-demand self-test. Possible causes for this fault are:
    • Low Battery Charge
    • Contaminated Or Faulty MAF Sensor Or Connector
    • Open In PWR GND Circuit To MAF Sensor
    • Open In MAF RTN Circuit To MAF Sensor
    • Faulty PCM

    Ensure MAF sensor is connected properly. Repair as necessary. Start engine and allow to idle. Using scan tool, access MAF V PID from PID/DATA MONITOR & RECORD menu. If MAF V PID voltage is .46-2.44 volts, no concern is indicated at this time. Check for intermittent concern. Go to TEST Z, step 1) . If MAF V PID voltage is not .46-2.44 volts, go to next step.

  4. 4) Check VPWR Voltage To MAF Sensor

    Turn ignition switch to OFF position. Disconnect MAF sensor. Turn ignition switch to ON position. Using a DVOM, measure voltage between negative battery terminal and MAF sensor harness connector VPWR terminal. See Fig 1-Fig 6 . If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, locate and repair open in VPWR circuit.

  5. 5) Check PWR GND Circuit Between MAF Sensor & Power Relay

    Using a DVOM, measure voltage between positive battery terminal and MAF sensor harness connector PWR GND terminal. See Fig 1-Fig 6 . If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, locate and repair open in PWR GND circuit.

  6. 6) Check VPWR Circuit For Open

    Turn ignition switch to OFF position. Leave MAF sensor disconnected. Disconnect PCM connector(s). On models with 150-pin PCM, measure resistance of VPWR circuit between MAF sensor harness connector and fuse between PCM power relay and MAF sensor. For appropriate fuse, see WIRING DIAGRAMS article. On all others, measure resistance of VPWR circuit between MAF sensor harness connector and PCM harness connector. See Fig 1-Fig 6 . On all models, if resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in VPWR circuit.

  7. 7) Check MAF Circuit For Short To PWR GND Or MAF RTN In Harness

    Ensure PCM is disconnected. Disconnect scan tool from Data Link Connector (DLC). Using a DVOM, measure resistance between MAF and PWR GND, and MAF RTN circuits at MAF sensor harness connector. See Fig 1-Fig 6 . If both resistance measurements are more than 10 k/ohms, go to next step. If either resistance measurement is 10 k/ohms or less, repair short to ground in affected circuit.

  8. 8) Check MAF RTN Circuit For Short To PWR GND In Harness

    Using a DVOM, measure resistance between MAF RTN and PWR GND circuits at MAF sensor harness connector. See Fig 1-Fig 6 . If resistance measurement is more than 10 k/ohms, reconnect scan tool and go to next step. If resistance measurement is 10 k/ohms or less, repair short to ground in affected circuit.

  9. 9) Check MAF Circuit Voltage Cycling Integrity

    Reconnect PCM harness connector(s). Turn ignition switch to ON position. Using scan tool, access MAF V PID from PID/DATA MONITOR & RECORD menu. Record MAF V PID reading. Connect a jumper wire between MAF sensor harness connector MAF RTN and PWR GND terminals, and another jumper wire between MAF sensor harness connector VPWR and MAF terminals. See Fig 1-Fig 6 . If MAF V PID reading changes from less than .23 volt to more than 4.5 volts, replace MAF sensor. If MAF V PID reading does not change from less than .23 volt to more than 4.5 volts, proceed as follows:
    • If DTC P1101 is present without DTC P0102, go to step  11).
    • If DTC P0102 is only DTC present, go to next step.

  10. 10) Check MAF Circuit For Open

    Turn ignition switch to OFF position. Disconnect PCM connector(s). Using a DVOM, measure resistance of MAF circuit between MAF sensor harness connector and PCM harness connector. See Fig 1-Fig 6 . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in MAF circuit.

  11. 11) Check PWR GND Circuit For Open In Harness

    Ensure ignition switch is turned to OFF position. Disconnect PCM connector(s). Disconnect scan tool from Data Link Connector (DLC). Using a DVOM, measure resistance of PWR GND circuit between MAF sensor harness connector and negative battery terminal. If resistance is less than 10 ohms, reconnect scan tool to DLC and go to next step. If resistance is 10 ohms or more, repair open in PWR GND circuit.

  12. 12) Check MAF RTN Circuit For Open In Harness

    Using a DVOM, measure resistance of MAF RTN circuit between MAF sensor harness connector and PCM harness connector. See Fig 1-Fig 6 . If resistance is less than 5 ohms, replace PCM. If resistance is 5 ohms or more, repair open in MAF RTN circuit.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 16). No test procedures have been omitted.
    13. NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  13. 16) Continuous Memory DTC P1100: Check MAF Circuit For Intermittent Voltage To PCM
    DTC P1100 indicates MAF signal exceeded maximum or fell below minimum calibrated limit during the last 40 warm-up cycles. Possible causes for this fault are:
    • Poor Continuity Through MAF Sensor Connector(s) Or Harness
    • Intermittent Open Or Short In MAF Sensor

    Start engine and allow to idle. If idle is not stable, see appropriate symptom under SYMPTOMS in TROUBLE SHOOTING - NO CODES - EEC-V - GASOLINE & NGV article. Raise engine speed to 1500 RPM for 5 seconds, then allow to return to idle. Using scan tool, access MAF V PID from PID/DATA MONITOR & RECORD menu. While observing MAF V PID, tap on MAF sensor and wiggle sensor harness connector to simulate road shock. If MAF V PID voltage reading fluctuates to less than .23 volt (minimum), or to more than 4.6 volts (maximum), inspect MAF sensor connector. Repair connector as necessary. If connector is okay, replace MAF sensor. If MAF V PID voltage reading does not fluctuate to less than .23 volt (minimum), or to more than 4.6 volts (maximum), go to next step.

  14. 17) Check MAF Sensor Circuit For Intermittent Opens Or Shorts

    Turn ignition switch to ON position. Using scan tool, access MAF V PID from PID/DATA MONITOR & RECORD menu. While observing MAF V PID, wiggle small sections of wiring harness starting at MAF sensor working toward PCM. If MAF V PID voltage reading changes to less than .23 volt (minimum), or to more than 4.6 volts (maximum), repair wiring harness as necessary. If MAF V PID voltage reading does not change to less than .23 volt (minimum), or to more than 4.6 volts (maximum), no concern is indicated at this time. Turn ignition switch to OFF position and go to TEST Z, step 1) .
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 17) to step 20). No test procedures have been omitted.
    15. NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  15. 20) DTC P0103: Check MAF Sensor Signal High Input To PCM
    DTC P0103 indicates MAF signal exceeded maximum calibrated limit during KOEO or KOER Comprehensive Component Monitor (CCM). Possible causes for this fault are:
    • Restricted (not blocked) MAF Sensor Screen
    • MAF Circuit Shorted To VPWR
    • Faulty MAF Sensor Or Connector
    • Faulty PCM

    Ensure air induction system is free of restrictions. Repair as necessary. Start engine and allow to idle. If KOER DTC P0505 is present, go to TEST KE, step 2) . Raise engine speed to 1500 RPM for 5 seconds then allow to return to idle. Using scan tool, access MAF V PID from PID/DATA MONITOR & RECORD menu. Ensure an incorrect MAF V PID reading of more than 4.60 volts still exists. Turn ignition switch to OFF position. Disconnect MAF sensor connector. Connect a jumper wire between MAF sensor harness connector PWR GND and MAF RTN terminals. See Fig 1-Fig 6 . Start engine and allow to idle. If MAF V PID reading does not drop to less than .23 volt, turn ignition switch to OFF position, disconnect jumper wire and go to next step. If MAF V PID reading drops to less than .23 volt, turn ignition switch to OFF position. Remove jumper wire and replace MAF sensor.

  16. 21) Check MAF Circuit For Short To VPWR In Harness

    Leave ignition switch turned to OFF position and MAF sensor disconnected. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Turn ignition switch to ON position. Using a DVOM, measure voltage between MAF and PWR GND circuits at PCM harness connector. See Figure, Figure and Fig 1-Fig 6 . If voltage is less than one volt, go to next step. If voltage is one volt or more, repair MAF circuit for short to power.
    17. NOTE: On models equipped with 150-pin PCM, perform following check on both VREF circuits.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 25). No test procedures have been omitted.

  17. 22) Check MAF Circuit For Short To VREF In Harness
    Turn ignition switch to OFF position. Using a DVOM, measure resistance between MAF and VREF circuits at PCM harness connector (both VREF circuits on 150-pin PCM). See WIRING DIAGRAMS article. If resistance is 10 k/ohms or less, repair short between MAF and VREF circuits. If resistance is more than 10 k/ohms and an idle concern is not present, replace PCM. If resistance is more than 10 k/ohms and an idle concern is still present, DO NOT diagnose DTC P0102 at this time. Check MAF sensor operation and compare MAF sensor voltages to voltages in MASS AIRFLOW table in SENSOR OPERATING RANGE CHARTS - EXCEPT VILLAGER article.
    18. NOTE: If vehicle has been driven from a higher to a lower altitude for diagnosing, 3 or 4 heavy accelerations at more than 1/2 throttle must be performed to allow BARO PID to update to current altitude. BARO PID must be within plus or minus 6 Hz (plus or minus 2 in. Hg). See Fig 7.
    NOTE: The BARO PID value measurement is actual barometric pressure for the altitude where vehicle is being tested. Weather conditions (high or low pressure areas) may change local barometric pressure by several in. Hg plus or minus 3 Hz (plus or minus one in. Hg).

  18. 25) DTC P0171, P0172, P0174, P0175, P1130, P1131, P1132, P1150, P1151, P1152 Or Lean Driveability Concerns: Check Lean Conditions Related To MAF Sensor
    DTCs P0171, P0172, P0174 and P0175 indicate a concern when adaptive fuel strategy senses a lean or rich condition beyond the minimum or maximum calibrated limit. DTCs P1130 and P1150 indicate when an HO2S fails to switch due to a circuit or fuel exceeding a calibrated limit. DTCs P1131, P1132, P1151 and P1152 indicate a concern when fuel control system does not detect HO2S switching for a calibrated time. Possible causes for these faults are:

    • Air Measurement System

      MAF sensor contaminated, damaged or malfunctioning.

    • Fuel System

      Fuel pressure regulator is leaking or malfunctioning. Fuel filter plugged or dirty. Fuel pump is weak or check valve leaking. Leaking or contaminated fuel injectors. Low fuel pressure or running out of fuel. EVAP canister purge valve leaking (when canister is "clean"). Fuel supply line restricted. Fuel rail pressure sensor (incorrect reading).

    • Air Induction System

      Air leaks after MAF sensor, vacuum leaks, PCV system leaking or sticking valve, or improperly seated engine oil dipstick.

    • Exhaust System

      Exhaust leaks before or near HO2S, such as; exhaust manifold gasket or mating gaskets.

    • EGR System

      Leaking EGR valve gasket or tube, stuck EGR valve, leaking diaphragm or EVR solenoid leaking vacuum.

    • Secondary Air Injection

      Damaged or malfunctioning secondary air injection system (mechanically stuck valve).

    • Engine Mechanical

      Engine oil overfilled, cam timing, cylinder compression or exhaust leaks before or near HO2S.

    Ensure MAF sensor is connected. Start engine and bring to normal operating temperature. Using scan tool, access BARO, LONGFT1, LONGFT2 and MAF V PIDs. Check the following:

    • Ensure BARO PID is about the same as barometric pressure measurement for location, day and altitude of area. See Fig 7.
    • Ensure BARO PID values in Keep Alive Memory have been updated. If vehicle is driven down from higher altitudes for diagnosing, complete 3 or 4 heavy accelerations at more than 1/2 throttle to allow BARO PID to update.
    • Ensure BARO PID is within plus or minus 6 Hz (plus or minus 2 in. Hg) of altitude value. Refer to illustration. See Fig 7.
    • Ensure LONGFT1, LONGFT2 PIDs for all injector banks at idle are not more than minus 12 percent.
    • Ensure MAF V PID at idle in gear or neutral is not more than 30 percent (no more than 1.1 volt) of normal MAF V listed in appropriate pin voltage/PID value chart in appropriate PIN VOLTAGE/PID VALUE CHARTS article.

    If 2 out of the 3 checks are not within specification, go to next step. If 2 out of the 3 checks are within specification and DTCs P0171, P0172, P0174, P0175, P1130, P1131, P1132, P1150, P1151 or P1152 are present, go to TEST H, step 42) (gasoline vehicles), or TEST HA, step 42) (natural gas vehicles). If 2 out of the 3 checks are within specification and no DTCs are present but driveability concern still exists, diagnose by symptom. See SYMPTOMS in TROUBLE SHOOTING - NO CODES - EEC-V - GASOLINE & NGV article.

    19. NOTE: OBD-II requirements call for a fuel system DTC to be set on some vehicles although a driveability concern may not be noticeable, with or without the MAF sensor disconnected. If this should occur and BARO, LONGFT1, LONGFT2 and MAF V PID indicate a MAF sensor concern, replace MAF sensor.

  19. 26) Check To Isolate MAF Sensor From Lean Driveability Occurrence
    Disconnect MAF sensor connector. Start engine and drive vehicle. If lean driveability symptom (lack of power, spark knock, detonation, buck, jerk or hesitation on acceleration) is gone, replace MAF sensor. If lean driveability symptom still exists and DTCs P0171, P0172, P0174, P0175, P1130, P1131, P1132, P1150, P1151 or P1152 are present, go to TEST H, step 42) (gasoline vehicles), or TEST HA, step 42) (natural gas vehicles). If lean driveability symptom did not disappear and no DTCs are present, diagnose by symptom. See SYMPTOMS under TROUBLE SHOOTING - NO CODES - EEC-V - GASOLINE & NGV article.
Fig 1: Identifying MAF Sensor Wiring Harness Connector & Circuits (Cougar 2.0L & Focus)
G00013249Courtesy of FORD MOTOR CO.
Fig 2: Identifying MAF Sensor Wiring Harness Connector & Circuits (Econoline, Escape, Excursion, Explorer Sport, Explorer Sport Trac, Mustang, Ranger, Sable, Super Duty Pickup 5.4L & 6.8L, Taurus & Windstar)
G00077806Courtesy of FORD MOTOR CO.
Fig 3: Identifying MAF Sensor Extension Connector & Circuits (Escort 2V)
G99B02599Courtesy of FORD MOTOR CO.
Fig 4: Identifying MAF Sensor Extension Connector & Circuits (Escort 4V)
G00013252Courtesy of FORD MOTOR CO.
Fig 5: Identifying MAF Sensor Wiring Harness Connector & Circuits (Models With 150-Pin PCM)
G00077807Courtesy of FORD MOTOR CO.
Fig 6: Identifying MAF Sensor Wiring Harness Connector & Circuits (All Others)
G00013251Courtesy of FORD MOTOR CO.
Fig 7: Barometric Pressure Conversion Chart
G00013248Courtesy of FORD MOTOR CO.
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