Marten or Stone Marten in Your Engine: How to Protect Your Car

In Belgium, stone martens and martens are responsible for several thousand car insurance claims every year. Severed cables, punctured hoses, torn-out insulation: damage that's often invisible from the outside, but whose bill can quickly exceed €500.

This guide explains why these animals target your vehicle, how to protect yourself effectively, and what your car insurance does — or doesn't — cover.

Stone marten or marten: who are these nocturnal visitors?

Two cousins, one and the same problem

The stone marten (Martes foina) and the pine marten (Martes martes) are two very closely related mustelids, difficult to tell apart with the naked eye. They're often confused, and for good reason: their behaviour and the damage they cause are almost identical.

Both are solitary, hunt at night and have an opportunistic lifestyle. Hedgerows, woodpiles, barns, attics: they adapt to almost any environment. In recent years, their population has been growing, particularly in semi-rural and suburban areas of Belgium. In other words: you don't need to live in the countryside to fall victim to them.

Why your engine attracts them: warmth, smells and territory

Contrary to popular belief, stone martens and martens don't chew cables out of appetite. They're not trying to "eat" your wiring harness.

What attracts them first is the warmth of the engine compartment: a warm, dry shelter, protected from predators, ideal for resting. Then comes the territorial dimension: these animals mark their passage with scent secretions. When a male detects the scent of a rival on your engine, he reacts aggressively, and your cables, hoses and insulation bear the brunt of this rivalry.

Good to know: car cables sometimes contain substances of organic origin (derivatives of oils or (fish) meal) that make them more appealing to these animals' sense of smell.

Spring, a high-risk season

While stone martens can venture under your bonnet all year round, the risk is highest in spring. The mating season intensifies males' territorial behaviour: they travel greater distances, mark their territory more, and react more aggressively to competing scents.

It's also the time of year when vehicles left stationary for several days after winter make particularly easy targets.

What damage can martens cause?

The usual targets: cables, hoses, insulation

Under the bonnet, stone martens and martens systematically go after the same components. The electrical cables of the engine wiring harness are their favourite target: flexible, accessible, and carrying those tell-tale scent marks that trigger their territorial instinct. Next come the hoses (coolant, windscreen washer or oil lines) and the insulating foam lining the engine compartment.

A severed cable can cause a complete breakdown, a short circuit or trigger unexplained warning lights. A punctured hose can lead to a fluid leak and damage the engine if not detected quickly.

Bills that add up fast

Damage caused by stone martens is rarely trivial and can exceed €500 per repair. The cost of repairs can even far exceed this amount.

In practice, a repair job can range from a few hundred euros for replacing a simple cable, to more than €800 as soon as an electronic control unit is affected. Not to mention towing costs if the vehicle is left immobilised.

The telltale signs

Does your car no longer start for no apparent reason? Do you notice unusual warning lights on the dashboard? Lift the bonnet and look carefully. The traces of a stone marten's visit are generally visible: gnawed or severed cables, scattered pieces of insulating foam, scratches on the plastic parts, or even food remains stored by the animal.

If you spot these signs, have your vehicle inspected by a professional before getting back on the road. Some damage, even partial, can compromise the vehicle's safety.

How can you effectively protect your vehicle?

There's no miracle solution against stone martens. But several measures, intelligently combined, can significantly reduce the risk. Here's an overview of the options available, from the simplest to the most technical (or most expensive).

An enclosed garage: solution number 1

This is the most effective and most obvious form of protection: parking your vehicle in an enclosed space. A lock-up, a closed garage or any shelter whose access points you can seal off eliminates most of the risk. Be careful though: a stone marten can squeeze through an opening just 6 cm in diameter. Remember to block or fit mesh over every gap, even the smallest ones.

This option isn't available to everyone. If you park outdoors, the following solutions become much more relevant.

Scent repellents

Sprays, granules, scented blocks based on ammonia, naphthalene or essential oils: scent repellents create an unpleasant environment for the animal and encourage it to seek shelter elsewhere. Their main advantage is how accessible they are, both in price and availability (supermarkets, garden centres, DIY stores).

Their limitation is real, though: effectiveness decreases over time, with rain and with engine heat. Regular reapplication is essential to maintain the deterrent effect. And their smell may also bother you.

Ultrasonic devices

Fitted under the bonnet or under the vehicle, these devices emit high-frequency sounds inaudible to humans but perceived as aggressive by mustelids. They offer a middle-ground solution, more durable than scent repellents.

One point to watch: stone martens and martens can get used to a constant emission. The most effective devices are those whose power and emission frequency vary randomly, making it harder for the animal to become accustomed to them.

High-voltage devices

Often more effective and more expensive, high-voltage devices consist of small plates installed in the engine compartment. On contact with the animal, they deliver a mild electric shock without injuring it, but enough to discourage it from coming back.

Installation must always be entrusted to a professional. Some models switch off when the bonnet is opened, others don't: check this point before carrying out any mechanical work on your vehicle. These devices represent a bigger investment (sometimes over €400), but offer long-lasting protection and can be reused if you change vehicles.

Physical protective sleeves

Independently of repellent devices, it's possible to mechanically protect the most exposed cables and hoses by wrapping them in reinforced sleeves made of braided material or aluminium. These sleeves create a physical barrier that a stone marten's teeth cannot easily get through.

This solution combines well with other devices for thorough protection.

Cleaning the engine compartment: a forgotten but essential reflex

If your vehicle has already had a visit from a stone marten, thoroughly clean the engine compartment before taking any other measures. The scent secretions left by the animal act as an invitation signal to other individuals: as long as the smell remains, the risk of a repeat visit stays high.

A suitable engine cleaner will remove these marks and let you start with a clean slate. Also avoid leaving food near your vehicle: pet food, food scraps or even compost can attract these opportunistic predators.

Stone martens and martens: protected animals

Faced with the damage caused by a stone marten, the temptation to get rid of it for good can be strong. Before acting, it's essential to know the Belgian legal framework, which varies by region.

Good to know: the stone marten and the pine marten are two legally distinct species. The pine marten (Martes martes) is a protected animal across the whole of Belgium: capturing, injuring or killing it is strictly prohibited.

For the stone marten (Martes foina), the legislation is more nuanced and depends on your region.

• In the Brussels-Capital Region, the stone marten is fully protected. The Order of 1 March 2012 on nature conservation prohibits any form of hunting, capture or elimination. You may only drive the animal away using non-lethal means.
• In Wallonia, the stone marten is not strictly protected, but hunting it remains subject to very strict conditions. Culling is only possible for public health or safety reasons, with authorisation. In practice, if a stone marten has taken up residence under your bonnet, you can scare it off or trap it to release it elsewhere, but you cannot kill it.
• In Flanders, in the event of significant, repeated damage, you can approach your local municipality. It may grant an exemption allowing designated officers to capture the animal and release it away from your property. This process remains regulated and cannot be carried out on an individual basis.

In short: whatever your region, the legal and ethical priority is to drive the stone marten away without harming it. The repellent devices described in the previous section fit fully within this framework.

Insurance and assistance: who covers the damage?

Third-party liability vs comprehensive cover: the difference that matters

The first thing to do after a claim: check what your insurance covers. And on this point, the distinction is clear.

Third-party liability insurance (compulsory in Belgium) only covers damage caused to third parties. It does not cover damage to your own vehicle. Stone marten bites therefore fall outside its scope.

To be compensated, you need comprehensive insurance (fully comp) or, depending on your contract's terms, a mini-comprehensive policy. These plans cover damage to your own vehicle, including damage caused by animals — under certain conditions.

Not all comprehensive policies are equal

This is where you need to be careful. Not all insurance companies treat stone marten damage in the same way. Some cover it explicitly under "contact with an animal". Others limit this guarantee to large wild animals (deer, wild boar) and exclude mustelids. Others still require direct physical contact with the animal to trigger compensation.

Before any claim arises, take the time to read your contract's general terms and conditions or contact your insurer to clarify this point. Once a claim has occurred, keep all evidence: photos of the damage, the garage's invoice, an inspection report if available.

If your vehicle is immobilised, Redion steps in

Damage caused by a stone marten can leave your vehicle immobilised without warning, sometimes far from home. This is exactly the kind of situation where car assistance cover makes all the difference.

If your Redion contract covers your vehicle, our teams step in to arrange recovery, towing to the most suitable garage, and if necessary, the continuation of your journey: a replacement vehicle, accommodation or repatriation of passengers.

A breakdown caused by an animal is still a breakdown. And like any breakdown, it deserves a quick, effective response, with no extra stress.

Also worth reading on the Redion blog: A cat under the bonnet: what should you do?

Frequently asked questions about stone martens and your car

Photo: © scigelova, Shutterstock