Many ECUs are not equipped with adequate tamper detection to detect having been modified, and then flashed back to stock before returning to a service center. This an extremely common practice in the auto enthusiast community.

Wouldn’t they need to demonstrate that the ECU modifications _caused_ the damage? Of course they have incentive to get out of the warranty, but isn’t the whole point of the act to prevent them from getting out of it _unless_ they can demonstrate your mods to the ECU caused the damage?

Technically, yes in the US, but that does not mean that they can't still deny you claiming a modification did it. You could then take them to court but here's the rub there.

Consider, how much just a single lawyer cost per hour I don't think it would be worth it a lot of the times unless the entire car was basically destroyed or something very expensive has failed to have enough value to justify it. Otherwise the repair is gonna be a lot times in a similar ballpark cost wise (for most cars) as a law suite.

-Edit- Moreover if the case is not decided quickly or settled it could also end up costing a lot more.

Okay sure but in that case the dealer/manufacturer is willing to _lie_. I.e. to claim that your actions caused it without any proof. At that point everything is a bit out the window. They could simply make up any justification to deny your claim if they're willing to lie. I don't really see what's so special about the ECU in this case.

Apple will won't honor their warranty if you jailbreak your phone which is kinda similar to modding the firmware on ECU. Do you think car companies are going to be any different if they can get away with it.

In the case of Apple it's pretty hard to justify the court costs for a 1000 dollar device. So Apple rarely has to prove that the Jail break was the cause of the failure. They technically can't deny warranty claim if a modification was not the cause of the failure. However, Apple operates basically by default for almost all failures if Jail Broken you get no warranty which is technically not legal.

> They could simply make up any justification to deny your claim if they're willing to lie.

Yes, but only if they think they can get away with it. This kind of thing happens all the time.

Arguably, the fact that the ECU was modified is evidence enough. It's pretty difficult to argue that an aftermarket stereo head unit, or air intake, or "ooga" horn caused engine damage. That would be a fairly easy win in court if the dealer is foolish enough to think anyone would buy that explanation.

Remapping an ECU is very different. If an ECU is remapped, that likely means the engine is operating outside of the intended parameters, and dealers would probably argue that the ECU is not intended to be modified by 3rd parties. From their perspective, why should they foot the bill for damage caused by changing how the engine functions? The dealer can deny your warranty claim because they know there's a 99.9% chance you won't fight it, and that you'll probably lose anyway if you do.

In the case of Mercedes and their paywall for faster acceleration, they could argue that any "hack" to enable faster acceleration is not only a form of piracy but that a hack could lead to dangerous situations; when say a bit is flipped to enable the acceleration, but the rest of the conditionals in the programming aren't aware of this change, the behavior of the vehicle can't be entirely predicted.

I don't necessarily agree with any of that reasoning, but this is how car companies not only defend their ability to deny warranty but extract more revenue from its customers going forward into the digital future.

Sounds like a great case to forcefully open-source it in court, so that all parties may inspect it.

And naturally, case law as well.