HU/AU Explained: What German Car Owners Should Know
HU and AU are often mentioned together, but many owners do not fully understand what each part covers.
By the Fahrnex Editorial Team · Reviewed by Umme Hanna Meskat
If you own a vehicle in Germany, you'll eventually encounter terms like HU, AU, and TÜV. For many expats and first-time vehicle owners, these terms can be confusing. Yet understanding them is essential because they determine whether your vehicle remains legally roadworthy.
HU focus
Main inspection
AU focus
Emissions check
Missing an inspection deadline can lead to fines, additional inspection fees, and potential complications if your vehicle develops safety-related issues.
In this guide, you'll learn:
- What HU and AU mean
- How Germany's vehicle inspection system works
- Which vehicles require inspections
- Typical costs and deadlines
- What happens if your TÜV expires
- How to prepare your vehicle and avoid common failures
Whether you're a long-term resident, company car driver, fleet manager, or new vehicle owner, this guide covers everything you need to know.
Prefer reading in German? See our complete guide: HU und AU in Deutschland erklärt: Alles, was Autofahrer wissen müssen.
What Is the Difference Between HU and AU?
The HU (Hauptuntersuchung) is Germany's mandatory roadworthiness inspection that checks whether a vehicle is safe and complies with legal requirements. The AU (Abgasuntersuchung) focuses on emissions testing and environmental compliance. Today, the AU is integrated into the HU process, but both terms are still commonly used together.
Keep the next vehicle deadline visible without scattered paperwork.
Fahrnex connects reminders, documents, and service history so inspections and maintenance are easier to plan before they become urgent.
Create a free accountWhat Do HU and AU Mean?
What Is the Hauptuntersuchung (HU)?
The Hauptuntersuchung, commonly abbreviated as HU, is Germany's mandatory technical inspection required under Section 29 of the German Road Traffic Licensing Regulations (StVZO §29).
The purpose of the inspection is to ensure that a vehicle:
After successfully passing the inspection, the vehicle receives a new inspection sticker displayed on the rear license plate.
Although many people refer to the inspection simply as "TÜV," several authorized organizations can perform the inspection.
These include:
- TÜV
- DEKRA
- GTÜ
- KÜS
What Is the Abgasuntersuchung (AU)?
The Abgasuntersuchung (AU) is Germany's emissions test.
Its purpose is to verify that a vehicle meets environmental regulations and emissions standards.
During the inspection, examiners may check:
Modern vehicles often undergo electronic diagnostics through the OBD system, allowing inspectors to identify emissions-related issues quickly.
Why Are HU and AU Usually Mentioned Together?
Historically, the emissions test and roadworthiness inspection were separate procedures.
Today, the AU forms part of the overall inspection process. However, the phrase "HU and AU" remains widely used by vehicle owners, workshops, and inspection organizations throughout Germany.
When people talk about:
they are usually referring to the combined HU/AU process.
Which Vehicles Require HU and AU in Germany?
Passenger Cars
Private passenger vehicles must undergo their first inspection three years after initial registration.
After that, inspections are required every two years.
Standard schedule:
Motorcycles
Motorcycles are also subject to regular inspections.
Typical interval:
Inspectors pay particular attention to:
- Brakes
- Tires
- Suspension
- Lighting systems
Commercial Vehicles
Commercial vehicles often face stricter inspection requirements.
Depending on vehicle type and weight, additional safety inspections may be required between regular HU appointments.
Fleet operators should carefully monitor all inspection deadlines.
Company Cars
For company and fleet vehicles, the interval follows the vehicle category, permitted mass and use rather than the identity of the owner.
Businesses operating multiple vehicles often use digital fleet management systems to track:
How Does a HU/AU Inspection Work?
Many vehicle owners are surprised by how thorough Germany's inspection process can be.
The inspection typically covers several key areas.
Document Verification
Inspectors first verify:
Any discrepancies can lead to additional checks.
Safety Inspection
The technical examination focuses on components that affect vehicle safety.
Braking System
Inspectors evaluate:
Brake defects can prevent an inspection sticker from being issued and must be handled according to the inspection report.
Lighting System
The following components are checked:
Even a simple burnt-out bulb can result in a defect notice.
Tires and Wheels
Inspectors assess:
German law generally requires at least 1.6 mm in the main tread. Damage, age, weather and intended use can require replacement before that legal limit is reached.
Steering and Suspension
The inspection includes:
Any wear affecting vehicle stability may result in failure.
Emissions Testing
During the AU portion of the inspection, emissions performance is evaluated.
The applicable measurement or OBD procedure depends on the vehicle and the rules in Annexes VIII and VIIIa. An active emissions-related warning should be professionally investigated before the appointment.
How Much Do HU and AU Cost in Germany?
The price depends on the vehicle, inspection organization, location and any additional examination. Because tariffs change, this guide does not present a fixed national price range.
Check the selected station's current tariff before booking and confirm whether emissions-system testing and any reinspection are included.
TÜV, DEKRA, GTÜ, and KÜS Comparison
TÜV
Germany's most recognized inspection organization with nationwide coverage.
DEKRA
Widely available throughout Germany and especially prominent in eastern regions.
GTÜ
Offers inspections through numerous partner workshops.
KÜS
Provides similar inspection services with extensive regional coverage.
All organizations must follow the same legal inspection standards.
What Happens If Your TÜV Expires?
The consequences depend on how long the inspection has been overdue.
If your inspection deadline has already passed, it's important to understand the potential consequences. Our detailed guide on what happens if your TÜV expires in Germany explains fines, penalties, additional inspections, and what steps to take to remain compliant.
Potential Consequences
Extended Inspection
This increases both the duration and cost of the appointment.
Re-Inspection
A re-inspection fee will usually apply.
Insurance Considerations
However, if a vehicle with known safety defects contributes to an accident, insurance disputes may arise.
Common Reasons Vehicles Fail the HU
Many failures result from relatively simple issues that could have been fixed beforehand.
Common reasons include:
Faulty Lighting
Brake Problems
Worn brake pads
Uneven braking performance
Damaged brake components
Tire Defects
Oil Leaks
Inspectors frequently identify:
Emissions Problems
Common causes include:
10 Practical Checks Before the HU and AU
A basic pre-check can reveal visible problems, but it cannot predict or replace the prescribed inspection.
1. Check all exterior lights.
2. Inspect tire tread depth.
3. Verify tire pressure.
4. Replace worn windshield wipers.
5. Top up all fluids.
6. Investigate dashboard warning lights.
7. Listen for brake noises.
8. Follow the inspection station's preparation instructions.
9. Bring all required vehicle documents.
10. Fix minor defects before your appointment.
A simple €5 bulb replacement today can save the inconvenience and cost of a re-inspection later.
Digital Vehicle Management and TÜV Reminders
Keeping track of inspections becomes increasingly difficult when managing multiple vehicles.
Keeping inspection reports, registration documents, insurance records, and maintenance receipts organized can significantly reduce administrative stress. Learn how to organize vehicle documents digitally and keep all important records accessible whenever you need them.
Digital vehicle management platforms such as Fahrnex help vehicle owners organize:
Automated reminders can reduce the risk of missing critical TÜV appointments and help maintain complete vehicle records.
Conclusion
HU and AU inspections are an essential part of vehicle ownership in Germany. They help ensure road safety, environmental compliance, and legal vehicle operation.
Understanding inspection schedules, costs, and preparation requirements can save time, money, and unnecessary stress.
By maintaining your vehicle properly and tracking important deadlines, you can significantly improve your chances of passing on the first attempt.
With Fahrnex, you can keep maintenance records, vehicle documents, and TÜV deadlines organized in one place.
Frequently asked questions
HU/AU Explained: What German Car Owners Should Know?+
HU and AU are often mentioned together, but many owners do not fully understand what each part covers.
What should drivers or fleet teams do next?+
Understand the role of both inspection elements before your appointment. Treat the inspection result as part of your ongoing maintenance record, not a one-off paper event. Fahrnex helps keep these tasks visible in one place.
How often do vehicles need a HU inspection in Germany?+
Most passenger cars require their first inspection three years after registration and every two years thereafter. Commercial vehicles may have different schedules depending on vehicle type and regulations.
Is the AU still mandatory?+
Yes. The emissions test remains mandatory and forms part of the overall HU inspection process. Vehicles must comply with current environmental standards to pass.
How much does a re-inspection cost?+
Most re-inspections cost between €15 and €40, depending on the inspection organization and the defects involved.
How long can you drive with an expired TÜV?+
Driving with an expired inspection sticker is not recommended. Penalties increase as the delay becomes longer, and significant delays may trigger additional inspection requirements.
Can you legally drive without a valid HU?+
The vehicle generally remains registered, but operating it without a valid inspection may result in fines and legal consequences. If serious defects are identified, authorities may restrict vehicle use.
In short
HU and AU often feel like one appointment in practice, but they cover different inspection focuses. That is why keeping the result documented matters.
About this article
Fahrnex evidence check
HU and emissions testing checked against German primary law
The review compared intervals, inspection scope, report retention and tyre claims with the current StVZO. Volatile provider prices and generic penalty figures were removed.
| Claim | Primary basis | Reviewed conclusion |
|---|---|---|
| HU scope and emissions | StVZO § 29 and Annexes VIII/VIIIa | HU covers road safety, environmental compatibility and applicable construction rules; emissions-system testing sits inside that framework, subject to stated exceptions. |
| Passenger car and motorcycle timing | StVZO Annex VIII 2.1.1–2.1.2 | Motorcycles generally use 24-month HU intervals; a new ordinary passenger car is generally 36 months first, then 24 months. Other categories can differ. |
| Report and tyre rule | StVZO § 29(10) and § 36(3) | Keep the report at least until the next HU; the main tread is generally required to have at least 1.6 mm. |
| Late inspection and prices | Current fines catalogue and inspection-station tariff | Consequences depend on delay and vehicle category; prices must be checked with the selected station. |
Reviewed on 28 August 2026
- Checked statutory intervals
- Separated HU law from preparation advice
- Removed unstable price ranges
- Added primary-law sources for tread and report retention
Editorially reviewed on 28 August 2026. Sources:
The editorial team checked official sources against the Fahrnex product methodology. This article is not a substitute for case-specific technical, legal or tax advice.
