A dirty or failing MAF (mass-airflow) sensor causes drivability complaints on the MAF-equipped GTIs (1.8T, FSI and others).
Symptoms:
- Hesitation, flat spots, poor economy, rough idle, sometimes limp mode.
- A classic tell: the car runs better with the MAF unplugged (it falls back to a default map) — that points at a bad MAF.
- MAF codes (P0101 / P0102) on VCDS.
The fix:
- Clean the element with proper MAF cleaner first (never touch it) — often cures a dirty one.
- If cleaning doesn't fix it, replace with a genuine/OE MAF (cheap sensors read poorly).
Note: some later engines are speed-density (no MAF) and use the manifold-pressure sensor instead.
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