Inspect routing first
Check the lines between the tank-breathing system and throttle body. Confirm the N80 quick-connect lines and leak-detection-pump vacuum line have not been crossed. Incorrect routing can also cause difficult starting after refueling.
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Choose the next test
Use the correct repair manual to test the applicable purge valve and canister. Ross-Tech references output tests and basic settings, but their commands and prerequisites depend on the controller. Do not activate an unrelated test simply because it is available.
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Check the applicable bulletin
North American A4 1.8T and Passat 1.8T have different cited software guidance. The page also identifies specific DGUE Tiguan and 1.4 Jetta cases. Match engine and year before treating any bulletin as the repair.
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Sources / references 1
- Ross-Tech fault reference ↗Reviewed Oct 8, 2026
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