Air Temperature Sensor ( Ambient / Intake ): Testing and Inspection

Intake Air Temperature Sensor, checking

- connect VAG 1551 Diagnostic tester
- start engine and let idle
- select Function "Read measuring value block"
or
- while observing VAG 1551 display, select the following functions in sequence
1 - Rapid data transfer
01 - Engine electronics
08 - Read measuring value block

- press 0 key twice to select "Display group number 02"
- display will appear as shown





- press 0 key to enter input
- display will appear as shown





- read display value in channel 1






Test A




- disconnect CO potentiometer harness connector (with sensor for intake air temperature and bridge terminals 2 and 3 of the connector using jumpers from VW 1594 adaptor kit
- displayed value must be 0

If YES
- Intake air temperature sensor control OK

- switch OFF ignition
- replace CO potentiometer (G 74) and intake air temperature sensor (G 42)
- activate fault memory and erase


Test B

- switch OFF ignition
- disconnect CO potentiometer harness connector



- measure sensor resistance across terminals 2 and 3 using US 1119 multimeter and jumper wires from VW 1594 adaptor kit
- measured value must fall within appropriate area of chart

If specified value obtained
- reconnect CO potentiometer harness connector
- check wiring for short circuit to control unit negative (-) using wiring diagram, repair or replace as necessary

If wiring OK
- replace Digifant control unit
- activate Fault memory and then erase

If the specified value not obtained
- replace CO potentiometer (G 74)
- comes complete with with intake air temperature sensor (G 72)
- activate Fault memory and then erase
- check idle speed and CO content, adjust if necessary