What is it and when to act?
The Hauptuntersuchung (HU) is the mandatory government safety and emissions inspection. When buying a used car, check the HU date first — in the Fahrzeugschein (Teil I) and on the number plate sticker. If the HU expires within 2 months, have it done before registering the car.
Where to book
Book online with TÜV or DEKRA — appointments are usually available within 1–2 weeks (also TÜV Nord, TÜV Rheinland, GTÜ, CITA depending on your region).
Common mistakes
I bought a car with the HU 'valid until end of month'. I didn't check — it had expired 3 days earlier. Police stop: €60 fine and a ban on driving until the HU was done. Always check the HU date before buying — it's a bargaining point.
My car failed the HU — the brakes were defective. I drove home 'just a short way' — the inspector had flagged gefährliche Mängel and banned the car from the road. I paid €120 for a tow truck. With gefährliche Mängel, don't move the car — tow it or fix it on the spot.