Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSVOLKSWAGEN1996JETTA (1H2) L4-2.0L (ABA)REPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSAIR TEMPERATURE SENSOR ( AMBIENT / INTAKE )TESTING AND INSPECTION
1996 Volkswagen Jetta (1H2) L4-2.0L (ABA)
Air Temperature Sensor ( Ambient / Intake ): Testing and Inspection
1996 Volkswagen Jetta (1H2) L4-2.0L (ABA)SECTION Testing and Inspection
Special Tools, Testers And Auxiliary Items
- VAG 1551/1552 Scan Tool With VAG 1551/3 Adapter Cable
- VAG 1598/18testbox
- Multimeter (Fluke 83 Or Equivalent)
- Connector Test Kit VW 1594
- Wiring Diagram
- Chilling Spray (Commercially Available)
Test Sequence
- Connect VAG 1551/1552 scan tool and select "Engine Electronics" address word 01, When doing this the ignition must be switched on.
Indicated on display
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08 and press -Q- button to confirm input.
Indicated on display
Read Measuring Value Block HELP
Input display group number XXX
- Press buttons -0-, -0- and -3- for display group 003 and press -Q- button to confirm input.
Indicated on display (1-4 Display fields)
Read Measuring Value Block 3-->
1 2 3 4
Display Group 003: Load Registration 1
- Check the specification for intake air temperature sensor (display field 4).
Evaluating Display Group 003
Checking Wiring
- Switch ignition off.
- Connect VAG 1598/18 test box to ECM wiring harness.
- Disconnect 2-pin connector -1- from Intake Air Temperature sensor -G72- -2-.
- Check wiring between test box and 2-pin connector for open circuit according to wiring diagram.
- Terminal 1 and test box socket 36
- Terminal 2 and test box socket 33
Resistance: Maximum 1.5 ohms
- Check wiring between test box and 2-pin connector terminal 2 for short circuit to wire terminal 1 or to vehicle Ground, according to wiring diagram.
- Terminal 2 and test box socket 36.
- Terminal 2 and vehicle Ground.
Specification: Infinite Ohms
- Additionally, check both wires for short circuit to battery positive (B+).
Specification: Infinite Ohms
If no malfunction in wiring is detected:
- Measure resistance at IAT sensor -G72- terminals 1 and 2, resistance values, see resistance chart listed below.
- The diagram applies to Engine Coolant Temperature sensor -G62- and intake Air Temperature sensor -G72-.
- Scale A shows resistance values for Temperature range 0°- 50°C (32°-122° F) and Scale B shows the values for Temperature range 50°-100°C (122°-212° F).
- If the specification is not attained:
- Replace IAT sensor -G72-.
Continuation Of Check When Display = Ambient Temperature
- Remove AT sensor (harness connector remains connected).
- Read intake air temperature value in display field 4.
- Spray sensor with a commercially available chilling spray and at the same time observe the temperature value.
- The temperature value must decrease.
If the specification is not attained:
- Replace AT sensor -G72-.
- Read the readiness code. If DTC memory has been erased, repair must be verified via appropriate display group: Readiness code, creating.
- VAG 1551/1552 Scan Tool With VAG 1551/3 Adapter Cable
- VAG 1598/18testbox
- Multimeter (Fluke 83 Or Equivalent)
- Connector Test Kit VW 1594
- Wiring Diagram
- Chilling Spray (Commercially Available)
Test Sequence
- Connect VAG 1551/1552 scan tool and select "Engine Electronics" address word 01, When doing this the ignition must be switched on.
Indicated on display
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08 and press -Q- button to confirm input.
Indicated on display
Read Measuring Value Block HELP
Input display group number XXX
- Press buttons -0-, -0- and -3- for display group 003 and press -Q- button to confirm input.
Indicated on display (1-4 Display fields)
Read Measuring Value Block 3-->
1 2 3 4
Display Group 003: Load Registration 1
- Check the specification for intake air temperature sensor (display field 4).
Evaluating Display Group 003
Checking Wiring
- Switch ignition off.
- Connect VAG 1598/18 test box to ECM wiring harness.
- Disconnect 2-pin connector -1- from Intake Air Temperature sensor -G72- -2-.
- Check wiring between test box and 2-pin connector for open circuit according to wiring diagram.
- Terminal 1 and test box socket 36
- Terminal 2 and test box socket 33
Resistance: Maximum 1.5 ohms
- Check wiring between test box and 2-pin connector terminal 2 for short circuit to wire terminal 1 or to vehicle Ground, according to wiring diagram.
- Terminal 2 and test box socket 36.
- Terminal 2 and vehicle Ground.
Specification: Infinite Ohms
- Additionally, check both wires for short circuit to battery positive (B+).
Specification: Infinite Ohms
If no malfunction in wiring is detected:
- Measure resistance at IAT sensor -G72- terminals 1 and 2, resistance values, see resistance chart listed below.
Sensor Resistance Chart:
- The diagram applies to Engine Coolant Temperature sensor -G62- and intake Air Temperature sensor -G72-.
- Scale A shows resistance values for Temperature range 0°- 50°C (32°-122° F) and Scale B shows the values for Temperature range 50°-100°C (122°-212° F).
- If the specification is not attained:
- Replace IAT sensor -G72-.
Continuation Of Check When Display = Ambient Temperature
- Remove AT sensor (harness connector remains connected).
- Read intake air temperature value in display field 4.
- Spray sensor with a commercially available chilling spray and at the same time observe the temperature value.
- The temperature value must decrease.
If the specification is not attained:
- Replace AT sensor -G72-.
- Read the readiness code. If DTC memory has been erased, repair must be verified via appropriate display group: Readiness code, creating.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.