Towbar fitting

Fixed, detachable or swivelling

A fixed towbar stays in place. It is the cheapest option and suits you if you use it often. The ball is always out, though, and it is easy to knock your shins on it behind the car.

The ball neck of a detachable towbar comes off and is kept in the car when it is not needed. All that stays under the bumper is the ball's mounting point, which hardly shows. A detachable towbar costs more than a fixed one, because it has a locking mount and a key. For some models there is also a swivelling towbar, turned out of sight under the bumper by hand or electrically.

The wiring kit and the socket

A 7-pin socket is enough for a trailer's basic lights: tail lights, brake lights, indicators and rear fog light. A caravan needs a 13-pin socket, which adds the reversing light and the permanent and charging supply. Trailers usually have a 7-pin plug, caravans and many bike racks a 13-pin one. An adapter links the two, but the socket is worth choosing by what you are going to hitch to the towbar.

A wiring kit is either vehicle-specific or universal. A vehicle-specific kit plugs into the car's own connectors, and through it the car usually recognises the trailer. The parking sensors then switch off when a trailer is attached, for example, and the trailer stability function works if the car has one. A universal kit is connected to the tail-light wires, and the car may then not recognise the trailer. On many new cars the trailer function also has to be coded into the car's control unit. The wiring kit and the coding depend on the car's equipment, so we always ask whether the car has parking sensors or a reversing camera.

How much the car may tow

The car's manufacturer states how heavy a trailer the car may tow. The maximum braked trailer mass is in the technical part of the registration certificate at field O.1, and the maximum unbraked mass at field O.2. The same figures are shown in Traficom's Oma asiointi service.

The maximum vertical load on the ball is not on the registration certificate. It is in the manufacturer's documents, usually the car's handbook. The towbar's own limits are marked on its type plate. Where the figures differ, the lower one decides.

The driving licence sets its own limit. A B licence lets you tow a trailer with a total mass of up to 750 kg. A heavier trailer is allowed too, if the total masses of car and trailer add up to no more than 3 500 kg. For the licence, what counts are the total masses entered in the register, not how much load is in the car or the trailer. If the car's data shows no trailer masses at all, we find out before ordering whether the car may tow a trailer.

Is a modification inspection needed

No. Traficom's regulation on modifying a car's structure allows a towbar to be fitted to a car or a van without a modification inspection, provided the towbar and its fitting meet the requirements that apply to them. That is why the towbar has to be approved for the car model and fitted to the manufacturer's instructions. Nor does a cut made in the bumper for the fitting need any explanation at the inspection.

How the work is done

1. We check the car's trailer masses and ask what you are going to tow. We choose the towbar and the wiring kit by the car model and its equipment.
2. We tell you the price. We order the parts once you have accepted it.
3. We remove the rear bumper or its lower part, and the underbody covers where needed. If the fitting instructions require it, we cut an opening in the lower edge of the bumper for the ball neck.
4. We fix the towbar to the car's mounting points and tighten the bolts to the specified torque.
5. We route the wiring kit under the boot trim, connect it to the car's electrical system and code the trailer function if the car requires it.
6. We refit the bumper and test every function of the socket and the parking sensors.
7. If the towbar is detachable, we show you how the ball is fitted and locked, and hand over the keys.

How long it takes

It depends on the car model: whether the bumper has to come off and be cut, whether the car has factory wiring for a towbar and whether the trailer function needs coding. Because the towbar and the wiring kit are ordered for the car model, we agree a time once we know which parts the car takes. We tell you then how long the car will be with us.

What the price depends on

• The type of towbar. A detachable towbar costs more than a fixed one.
• The wiring kit. A vehicle-specific kit usually costs more than a universal one, and a 13-pin kit more than a 7-pin one.
• The car's equipment. Parking sensors, a camera and coding the trailer function affect how the electrics are connected and how long it takes.
• Bumper and trim. Removing and cutting the bumper, underbody covers and boot trim add to the time.
• The state of the mounting points. On an older car, rust or seized bolts can call for extra work.

We check the car and tell you the price before the work starts. If the mounting points have rust or anything else that needs repairing, we tell you about it and the price of the repair before we go on.

The towbar and the inspection

The inspection also checks coupling devices. Faults are rare: according to Traficom's statistics, faults in coupling devices led to 198 rejections and 41 repair notices in the 2025 inspections. So when a towbar has a fault, the car is rejected more often than it gets a repair notice. If an old towbar's mountings are rusty or the towbar moves, the fault is worth fixing before the inspection.

What you can check yourself

• Look at the registration certificate or the Oma asiointi service to see how much the car may tow.
• Look up the ball's maximum vertical load in the handbook. The bike rack and the bikes together must not weigh more. With electric bikes the limit comes up quickly.
• Check whether the trailer, the caravan or the bike rack has a 7-pin or a 13-pin plug.
• With a detachable towbar, check every time before you set off that the ball has locked in place and the lock is closed with the key.
• Test the lights every time you hitch a trailer: tail lights, brake lights and both indicators. It is easiest with someone watching behind the trailer.

When not to tow

Do not set off with a trailer if

• a detachable towbar will not lock, or its lock indicator does not show the locked position
• the towbar moves in its mounting, or there are cracks or rust holes at the mounting points
• the trailer's brake lights or indicators do not work
• the trailer with its load is heavier than the car may tow, or the nose weight is more than the ball's vertical load allows.

A loose towbar and dark brake lights are safety faults. The driver behind cannot see you brake, and a trailer that comes loose is a danger to everyone. If the fault is in the towbar or the car's electrics, book a time and bring the car to the workshop without the trailer.