In order to place a professional electronics product inside a car or other vehicle moving in traffic, it has to be put through mandatory type approval, a test carried out by a neutral 3rd party test house which checks if your product conforms to elector-magnetic compatibility (EMC) requirements. The car (part) manufacturer would get a test report as proof of compliance. This is regulated pretty well world-wide by something called "UN ECE R10", a UN directive which is in turn widely adopted by many countries around the world (but apparently not by the USA).

Now since I work in electronics and is a regular user of for example electronics.stackexchange.com, I often encounter questions where someone is asking how to go about to place "hobbyist" electronics boards (Arduino, Rasp Pi etc) in cars or other vehicles. These are clearly not type approved and in addition are quite unlikely to fulfill the somewhat tough EMC requirements laid out by ECE R10 technical standards, since these are tougher than regular requirements on commercial electronics. And so these hobbyist projects always come with a risk of affecting other parts on the car, even if the hobbyist board itself isn't directly involved with a safety-critical function.

I would imagine that the situation is similar to someone modifying a vehicle to put their own home-made brakes in it. If these fail, then regular vehicle inspection would easily recognize this and require that you (the owner of the car) fix it. Except for electronics, the vehicle inspection or the police won't be able to tell the cause on-site - suppose the hobbyist board disrupts the ABS electronic brake system for example. They can tell that the brakes aren't working/failed but not why.

I am wondering what the legal consequences are for putting hobbyist boards in a car without going through type approval. Often it is someone modding their own car or motorcycle: I'm asking for scenarios where the modification has been carried out by an individual, not by a company who has put a product on market. Suppose we narrow it down to a few scenarios - will there be legal consequences in the following situations:

  • The authorities find out about the non-approved electronics "preemptively". No accident has occurred but the device poses a risk.
  • There was a serious accident (death or injury) caused by failing electronics on the car, but not obviously related to the hobbyist board. Suppose the ABS brake system failed but the hobbyist board is controlling the tail lights in the other side of the car.
  • There was a serious accident (death or injury) caused by failing electronics and the hobbyist board is found to be the direct cause. Suppose for example that the hobbyist board jammed critical CAN bus communication on board, so that the wheel no longer responds. And that this can be proven by recorded logs.

I'm also interested to know if there any examples of similar or even precedent cases? Mainly interested in EU and/or US. I'm aware of various famous lawsuits in the US where software or electronics have caused car accidents, but there the defendant has always been the car manufacturer and not individuals who have modded their own car.

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    Such a modification will likely void the insurance, unless the insurer is informed about it and agrees to insure the car.
    – Lag
    Sep 5, 2023 at 9:14
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    this highly depends on what the part does. Is it just a fancy "I light up the dashboard when not driving in rainbow colors" or is it "I tune the motor to inch out half a watt more power"? Is the part "safety critical" such as breaks or is it only cosmetic, such as the radio? Is it inside the car or outside? Is it a shoddy attempt to mimic a commercial part or is it properly done in a workshop from similar materials, just not certified? All those influence legality.
    – Trish
    Sep 5, 2023 at 9:17
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    @Trish The point which I tried to make in detail here is that you can't reason about electronics like that. It isn't possible to claim "it just lights up the dashboard", since any electrical device comes with radiated and conducted emissions that may disrupt other electronics on the vehicle. As for who carries out the installation, I really don't see how it matters if you haven't put the device through EMC testing.
    – Lundin
    Sep 5, 2023 at 9:19
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    @Trish If a product is only active when not moving through traffic, an exception from UN ECE R10 might be carried out, so that's not relevant here. Furthermore, for example some generic hobbyist device mounted next to safety-critical parts like the ECU or ABS module etc is probably less likely to cause harmful interference than say some home-made wireless device mounted around the seats, for the intended purpose of "harmless fun" transmitting music to some speakers, while also broadcasting a high radio frequency disturbance throughout the whole car.
    – Lundin
    Sep 5, 2023 at 9:26
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    Please note that I'm not really asking about how to establish if something is causing interference or not - I would imagine that this would be quite an intricate procedure in many cases. Hence one of the described scenarios is: what are the consequences if it is established and proven that the hobbyist device was the cause.
    – Lundin
    Sep 5, 2023 at 9:47


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