Test sequence

• Connect Scan Tool VAG1551 ( VAG1552 ) and select engine electronics control unit. Run engine at idle speed and press buttons 0 and 1 to select "Engine electronics" address word 01. (Connecting Scan Tool and selecting engine electronics control unit → Scan Tool VAG1551 , connecting  .)

Indicated on display:

• Press buttons 0 and 8 for the function "Read measured value block" and confirm entry with Q button.

Indicated on display:

• Press buttons 0 , 1 and 0 for "Display group number 10" and confirm entry with Q button.
• Observe display in display field 1.

• Specification: 230 to 370 mg/H

  Read measured value block 10 → 309 mg/H 1027 mbar 1011 mbar 0.0 %

If the specification is not obtained:

• Check exhaust gas recirculation: → 26 - EXHAUST SYSTEM, EMISSION CONTROLS

If the specification is obtained:

• Road test vehicle with a 2nd technician to observe display.

Observe valid safety precautions when road testing → Safety precautions  .

• Accelerate vehicle in 3rd gear (vehicles with manual transmission) or 2nd gear (vehicles with automatic transmission) from about 1500 rpm using wide open throttle.
• Press PRINT button on VAG1551 at approx. 3000 rpm. The accelerator pedal must be fully depressed at this moment in time.

• Specification in display field 4: 100% (accelerator pedal position/throttle)

  Read measured value block 10 → 830 mg/H 1027 mbar 1850 mbar 100 %

If the specification is not obtained:

• Repeat test and accelerate vehicle at wide open throttle.

• Specification in display field 1: above 800 mg/H (mass air flow drawn in).

  Read measured value block 10 → 830 mg/H 1027 mbar 1850 mbar 100 %

If the specification is not obtained:

• Press the → button.
• Press buttons 0 and 6 to select "End output" function 06 and confirm entry with the Q button.
• Switch off ignition.
• Replace MAF sensor.

• Check DTC memory and, if necessary, repair any malfunctions and then erase → Diagnostic Trouble Code (DTC) memory, checking and erasing  .
• Read readiness code → Reading readiness code  . If the DTC memory has been erased, the readiness code must be generated again → Readiness code, setting  .

If a constant 550 mg/H (predetermined replacement value) is displayed in display field 1.

• Press the → button.
• Press buttons 0 and 6 for the function "End output" and confirm entry with the Q button.
• Switch off ignition.

Fig 1: Locating MAF Sensor

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• Pull 5-pin connector off MAF sensor - arrow  -.
• Switch on ignition.

Fig 2: 5-Pin Connector & Terminals

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• Measure MAF sensor voltage supply between following connector contacts:

If specifications are not obtained:

• Switch off ignition.
• Remove wiper arms and plenum cover: → 92 WINDSHIELD WIPER & WASHER SYSTEM

Fig 3: Identifying Test Box V.A.G 1598/31 Connected To Control Module Wiring Harness

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• Connect test box VAG1598/31 to control module wiring harness.

Fig 4: 5-Pin Connector & Terminals

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• Check wiring between test box and connector for open circuit using wiring diagram.

Terminal 2+ socket 1 and 2

Terminal 3+ socket 49

Terminal 4+ socket 30

Terminal 5+ socket 68

Wire resistance: max. 1.5 Ω

• Check wires for short to one another, to vehicle Ground and to battery positive (B+).

Specification: ∞Ω

If no malfunction is detected in the wiring:

• Replace Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) J248 → Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) J248 , replacing  .