Work sequence

• Connect V.A.G 1551/1552 (Connecting scan tool and selecting engine electronics control module → Scan Tool V.A.G 1551 , connecting  .)
• Run engine at idle speed and press buttons - 0  - and - 1  - to select "Engine electronics" address word 01.

Indicated on display

• Press buttons - 0  - and - 8  - to select "Read measured value block" function 08 and confirm entry with - Q  - button.

Indicated on display

• Press buttons - 0  - , - 0  - and - 7  - to select "Display group number 7" and confirm entry with - Q  - button.

Indicated on display

• Check intake air temperature value in display field 3.

• The temperature value must be approx. ambient temperature.

If a malfunction is present, a constant 136.8 ° C will be displayed for the intake air temperature.

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

If display in field 3 appears unrealistic or a substitute temperature of 136.8 ° C is displayed, check IAT sensor and wiring as follows:

Fig 1: Locating Intake Air Temperature Sensor G72

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• Disconnect 4-pin connector from Manifold Absolute Pressure (MAP) Sensor G71 with IAT Sensor G72 - arrow  -.

Fig 2: 4-Pin Sensor Connector & Terminals

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• Measure resistance between sensor terminals 1 + 2.

Fig 3: Resistance Values Graph

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• Specification: correlate resistance measurement with chart

Examples:

• 30 ° C corresponds to a resistance from 1500 to 2000 Ω
• 80 ° C corresponds to a resistance from 275 to 375 Ω

If specification is not obtained:

• Replace MAP sensor G71 together with IAT sensor G72.
• Check DTC memory and, if necessary, repair any malfunctions and then erase → Diagnostic Trouble Code (DTC) memory, checking and erasing  .
• Read readiness code → Readiness code, displaying  .

If DTC memory has been erased, the readiness code must be generated again → Readiness code, setting  .

If specification is obtained:

• Remove wiper arms and plenum cover. →92 WINDSHIELD WIPER & WASHER SYSTEM

Fig 4: Identifying Test Box V.A.G 1598/22 Connected To Control Module Wiring Harness

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• Connect test box V.A.G 1598/22 (through my 1999) or test box V.A.G 1598/31 (from my 2000) to control module wiring harness.

Fig 5: Identifying Connector Terminals 1 And 4

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

• Wire resistance: max. 1.5 Ω

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

• Specification: ∞ Ω

If wiring and the resistance measurement values are OK:

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