Leak Detection Sensor: Testing and Inspection

Checking Sensor Function for EVAP canister
- Use VAG 1551 scan tool to select "Read Measuring Block Value" function 08 and display group 030, refer to Diagnosis with Scan Tool, Address Word 01/ Read measuring block value Testing and Inspection

Indicated on display

Read measuring value block 30
1 2 3 4

- Carry out test drive.

CAUTION: Always use a second person to operate the VAG 1557 scan tool.

- C heck value in display field 4.
- Specified value: 0_11X

- If display shows 0_OOX
On Board Diagnostic program is not yet concluded.

- Carry out test drive under conditions described in Repair Group 01, until display shows 0_11x.

- If display shows 1_11X
- This indicates how On Board Diagnostic recognizes a malfunction in the fuel tank system.
- Check vacuum hose for leakage between EVAP canister and throttle body, Vacuum and Vapor Hose Diagrams.

- If vacuum hose is OK:
- Remove harness connector from sensor for EVAP canister.
- Switch multimeter (Fluke 83 or equivalent) to 20 volt range and connect between harness connector terminals 1 (GND) and 3 (B+).
- Switch ignition ON - Specified value: approx. 5 volts

- If the specified value is not obtained:
- Check wiring to ECM.
- Connect VAG 1598/19 test box to ECM, Testing and Inspection.
- Check following wiring connections for continuity.

Sensor -G172- connector VAG 1598/19 test box
terminal number socket number
1 C2
3 C6

- If necessary, eliminate open or short in wiring.

- If wiring is OK and there is not at least 5 volts at the sensor harness connector:
- Replace ECM.
- Check wiring for continuity between harness connector and ECM.
- If necessary, eliminate open or short in wiring. If wiring is OK:
- Replace sensor for EVAP canister -G172-.