Every year, the same story: a driver shows up for the annual technical inspection fully confident, and walks out with a fail stamp. The reasons are surprisingly predictable. In most cases these are things that take an hour or two to fix, but nobody checked before the appointment. Instead of learning from your own mistake, here is a concrete breakdown of what inspectors find most often and what you can do the day before to avoid it.
Lights and Signals Are the Most Common Fail
It sounds trivial, but more than a third of inspection failures start with bulbs. A single burned-out brake light bulb, a faulty turn signal, or misaligned headlight beams are enough for a fail. The inspector checks every individual light: parking lights, low beam, high beam, fog lights, brake lights, license plate light, turn signals, interior cabin light, and the reverse light.
A particularly common problem is headlight beam alignment. If you have replaced bulbs, carried a heavy load, or had front suspension work done, the beam shifts and starts blinding oncoming drivers. At the inspection this is measured with a beam tester and only a properly aimed beam passes.
Another trap drivers do not think about: retrofit LED bulbs in halogen headlights. Many people buy LED bulbs because they shine brighter, but install them in a reflector designed for a halogen bulb. The result is a scattered beam that blinds others and does not pass the inspection. If you are planning a bulb change, read more about what to choose in the headlight bulb guide.
Brakes: Left-to-Right Force Difference
Brake pads and discs have prescribed minimum thicknesses that the inspector measures. Worn pads or discs with deep grooves are an automatic fail. But many drivers forget the second criterion that is equally common as a fail reason: the difference in braking force between the left and right side.
The car is tested on a brake roller bench. If one side brakes significantly harder than the other, the vehicle fails regardless of pad thickness. The most common causes of uneven braking are seized caliper slide pins, contaminated or corroded caliper pistons, or unevenly worn discs. The symptom while driving is the car pulling to one side under braking.
The handbrake is a separate item. The inspector checks whether the handbrake holds the vehicle on a slope. If it slips or requires too many clicks on the lever, that is a fail. On vehicles with rear drum brakes, this is even more common because the handbrake cables stretch over time. More on symptoms and checking brakes in the brake service guide.
Suspension: Clunking Means a Fail
Worn ball joints, tie rod ends, bushings, or shock absorbers create play that the inspector detects on the vibration plate or by pulling the wheel by hand with the car on a lift. Any dead zone or clunking and the vehicle fails.
While driving, you notice this as clunking over bumps, instability when changing lanes, or uneven tire wear with heavier wear on one edge. On older vehicles or those driven on rougher roads, the suspension is a regular fail reason. The problem is that wear accumulates gradually and the driver gets used to the noise, no longer noticing it. The inspector at the station notices immediately.
Emissions and Diesel Smoke
The inspector measures gases at the tailpipe. On petrol engines, CO and HC levels in the exhaust are measured. If combustion is incomplete due to a faulty oxygen sensor, a clogged catalytic converter, or ignition problems, the readings exceed the allowed limits and the car fails.
On diesel engines the situation is even stricter. Exhaust opacity is measured. A clogged DPF filter, a faulty EGR valve, or worn injectors produce visible black or grey smoke that does not pass the test. This is especially common on vehicles driven mostly on short urban trips because the DPF never gets a chance to regenerate. If your car occasionally loses power or enters a protective operating mode, that is a sign the exhaust system needs checking before the inspection.
Tires, Corrosion, and Surprise Details
Tires must have at least 1.6 mm of tread depth (the legal minimum), and in winter, winter tires with at least 4 mm. Tires on the same axle must be the same size and type. Mixing different sizes or types (radial and diagonal) on one axle is a fail. Likewise, a tire with visible sidewall damage (a bulge, a cut) fails regardless of tread depth.
Structural corrosion is a fail reason that surprises owners of vehicles ten or more years old. The inspector visually checks the sills, floor panels, engine mounts, jack points, and other structural elements. If corrosion has eaten through the metal or significantly weakened the structure, the vehicle fails. This is hard to fix quickly and usually requires body shop work.
Small details that drivers forget: a non-working horn, worn wiper blades that do not clear the windshield, a crack in the windshield within the driver's field of vision, a missing warning triangle or first-aid kit in the vehicle, and a faulty license plate light. Any of these can be a fail reason.
What to Check the Day Before and How to Pass First Try
Most fail reasons are things you can detect yourself if you spend twenty minutes the day before the inspection:
- Walk around the car with the engine running while someone presses the brake and activates the turn signals. Check every bulb in turn.
- Test the handbrake on a slight slope. If the car slides, the handbrake is weak.
- Listen for clunking on rough ground. If it clunks, the suspension needs checking.
- Look at the tires: tread depth, matching sizes on each axle, no sidewall bulges.
- Check the wiper blades, horn, warning triangle, and first-aid kit.
However, some things you cannot check on your own: headlight beam alignment, exact pad thickness, the condition of inner joints, engine emissions, and corrosion in hidden spots. For that you need a lift, tools, and experience. The best approach is to bring the car in for a pre-inspection service a week or two early. The mechanic goes through every item that gets checked at the inspection and tells you exactly what needs fixing. That way you avoid paying for the inspection twice (fail plus retest), stress on registration day, and multiple trips to the shop.
If your registration is coming up and you are not sure about the car's condition, book an appointment and take care of everything before it is time for the inspection.