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Home >> Mazda >> 2001 >> B2500 SE, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> System Tests >> Test Dc: Mass Airflow Sensor >> Diagnostic Aids

Diagnostic Aids

Perform this test when directed by QUICK TEST. This test is intended to diagnose the following:

To prevent replacement of good components, be aware the following non-EEC related areas may be cause of problem:

NOTE: If the following test steps fail to diagnose MAF sensor problem, compare MAF sensor voltages with MASS AIRFLOW table in SENSOR OPERATING RANGE CHARTS article.

  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 these faults 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 P1101, turn ignition switch to OFF position and go to step  3). If any Continuous Memory DTCs are present with KOER 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. 2) KOER & Continuous Memory DTC P0102: Low MAF Sensor Signal Input To PCM

    DTC P0102 indicates MAF signal 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 Sesnor)
    • 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. If no problems are detected, start engine and allow to idle. Check for 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 return to idle. Using scan tool, select MAF V PID from PID/DATA MONITOR & RECORD menu. If MAF V PID voltage is less than .23 volt, turn ignition switch to OFF position and 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 use of a garage exhaust ventilation system. Ensure vehicle is vented to outside atmosphere before repeating QUICK TEST .

  3. 3) KOEO DTC P1101: MAF Sensor Signal Out Of Self-Test Range
    Ensure MAF sensor is connected properly. If MAF sensor is not connected properly, repair as necessary. Start engine and allow it to idle. Using scan tool, select MAF V PID from PID/DATA MONITOR & RECORD menu. If MAF V PID voltage is .46-2.44 volts, no problem is indicated at this time. Check for intermittent problem. Go to TEST Z, step  1). If MAF V PID voltage is not .46-2.44 volts, turn ignition switch to OFF position and 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 or Fig 2 . 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 or Fig 2 . 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). Measure resistance between MAF sensor harness connector VPWR terminal and PCM harness connector VPWR terminal. See Fig 1 or Fig 2 . 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 Circuit

    Ensure PCM is disconnected. Disconnect scan tool from Data Link Connector (DLC). Using a DVOM, measure resistance between MAF sensor harness connector PWR GND terminals and MAF terminal. Using a DVOM, measure resistance between MAF sensor harness connector MAF RTN terminal and MAF terminal. See Fig 1 or Fig 2 . If all resistance measurements are more than 10 k/ohms, go to next step. If any 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 Circuit

    Using a DVOM, measure resistance between MAF sensor harness connector MAF RTN and PWR GND terminals. See Fig 1 or Fig 2 . If all resistance measurements are more than 10 k/ohms, reconnect scan tool and go to next step. If any 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, select MAF V PID from PID/DATA MONITOR & RECORD menu. Record MAF V PID voltage reading. Connect a jumper wire between MAF sensor harness connector MAF RTN and PWR GND terminals. See Fig 1 or Fig 2 .

    Connect another jumper wire between MAF sensor harness connector VPWR and MAF terminals. Compare MAF V PID voltage readings. If MAF V PID voltage reading changes from less than .23 volt to more than 4.5 volts, replace MAF sensor. If MAF V PID voltage 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 terminal and PCM harness connector terminal. See Fig 1 or Fig 2 . 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 Resistance

    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 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

    Using a DVOM, measure resistance of MAF RTN circuit between MAF sensor harness connector and PCM harness connector. See Fig 1 or Fig 2 . If resistance is less than 5 ohms, go to next step. 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. 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 it to idle. If idle is not stable, see appropriate symptom under SYMPTOMS in TROUBLE SHOOTING - NO CODES article. Raise engine speed to 1500 RPM for 5 seconds, then return to idle. Using scan tool, select 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 changes 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 change to less than .23 volt (minimum) to more than 4.6 volts (maximum), go to next step.

  14. 17) Check MAF Circuit For Intermittent Open Or Short

    Turn ignition switch to ON position. Using scan tool, select 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) to more than 4.6 volts (maximum), no problem 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. 20) DTC P0103: Check MAF Sensor Signal High Input To PCM

    DTC P0103 indicates MAF signal rose exceeded maximum calibrated limit during KOEO or KOER Comprehensive Component Monitor (CCM). Possible causes for this fault are:
    • Restricted MAF Sensor Screen
    • MAF Circuit Shorted To VPWR
    • Faulty MAF Sensor Or Connector
    • Faulty PCM

    Ensure air induction system is okay. Repair if necessary. Start engine and allow to idle. If engine does not idle smoothly, repair cause of rough idle condition before continuing. If KOER DTC P0505 is present, go to TEST KE, step  2). On B2500 A/T, if engine stalls or cannot maintain idle, replace PCM. On all models, if engine idles smoothly, raise engine speed to 1500 RPM for 5 seconds then return to idle. Using scan tool, select MAF V PID from PID/DATA MONITOR & RECORD menu. MAF V PID voltage reading should be more than 4.60 volts. 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 or Fig 2 . Start engine and allow to idle. Select and monitor MAF V PID from PID/DATA MONITOR & RECORD menu. If MAF V PID voltage 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 voltage 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

    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 PCM harness connector MAF and PWR GND terminals. See Fig 1 or Fig 2 . If voltage is less than one volt, go to next step. If voltage is one volt or more, repair MAF circuit short to VPWR.

  17. 22) Check MAF Circuit For Short To VREF

    Using a DVOM, measure resistance between PCM harness connector MAF and VREF terminals. See WIRING DIAGRAMS article. If resistance is more than 10 k/ohms and an idle problem is still present, DO NOT diagnose DTC P0103 at this time. Check MAF sensor operation and compare MAF sensor voltages with MASS AIRFLOW table in SENSOR OPERATING RANGE CHARTS article. If resistance is more than 10 k/ohms and an idle problem is not present, replace PCM. If resistance is 10 k/ohms or less, repair short between MAF and 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.
    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 3.

  18. 25) DTC P0171, P0172, P0174, P0175, P1130, P1131, P1132, P1150, P1151, P1152 Or Lean Driveability Problems: Check Lean Conditions Related To MAF Sensor

    DTCs P0171, P0172, P0174 and P0175 indicate a problem 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 problem when fuel control system does not detect HEGO switching for a calibrated time. Possible causes for these faults are:

    • Fuel System

      Excessive fuel pressure, leaking or contaminated fuel injectors, leaking fuel pressure regulator, low fuel pressure or engine running out of fuel or vapory recovery system fault.

    • Induction System

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

    • EGR System

      Leaking gasket, stuck EGR valve or leaking diaphragm or EVR.

    • Engine Mechanical

      Engine oil overfilled, cam timing, cylinder compression or exhaust leaks before or near HO2S.
    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. of Hg plus or minus 3 Hz. (plus or minus 1 in. Hg).

    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 3.
    • 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 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). If 2 out of the 3 checks are within specification and no DTCs are present but drivability problem still exists, diagnose by symptom. See SYMPTOMS in TROUBLE SHOOTING - NO CODES article.

    19. NOTE: OBD-II requirements call for a fuel system DTC to be set on some vehicles although a driveability problem 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 problem, replace MAF sensor.

  19. 26) Isolate MAF Sensor From Lean Driveability Problem
    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 did not disappear and DTCs P0171, P0172, P0174, P0175, P1130, P1131, P1132, P1150, P1151 or P1152 are present, go to TEST H, step  42). If lean driveability symptom did not disappear and no DTCs are present, diagnose by symptom. See SYMPTOMS under TROUBLE SHOOTING - NO CODES article.
Fig 1: Identifying MAF Sensor Wiring Harness Connector & Circuits (Except Tribute)
G00013251Courtesy of FORD MOTOR CO.
Fig 2: Identifying MAF Sensor Wiring Harness Connector & Circuits (Tribute)
G99E02082Courtesy of FORD MOTOR CO.
Fig 3: Barometric Pressure Conversion Chart
G00013248Courtesy of FORD MOTOR CO.
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