It's not quite as straight forward when it comes to ECU reprogramming/tuning. While it seems legal to modify an ECU or use an aftermarket ECU, states like California now won't allow cars with these sorts of mods to pass smog tests, and there's nothing to stop manufacturers from voiding your warranty for soft-modifying the ECU. It's a small leap for states to decide that not having the latest ECU firmware causes a failed smog test or even an "emissions fine" regardless of the actual exhaust composition.
> states like California now won't allow cars with these sorts of mods to pass smog tests
Thankfully, a lot of us live in better-governed states than California. And even if it is illegal where you live, stuff you own shouldn't try to enforce laws against you.
Generally speaking, yes, unless a dealer believes they can blame your modification for the issue. The ECU affects the entire powertrain, so there's incentive for the dealer to blame the mod for even just a cracked engine mount, while counting on you paying for a repair as opposed to filing a lawsuit.
After all, your engine must have been running hot and accelerated the wear on the mount. Oh, logging shows it wasn't? Must be a malfunctioning thermostat. That'll be $3,000 for the mount, the thermostat, and the labor. Not including any extra charges, fees, surcharges, taxes, or overcharges.
Car dealers are no different from insurance companies. Whether it's warranty or insurance, they make money by denying claims. The ECU is enough of a black box that practically anything critical can be blamed on it if it's not using factory settings.
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.
> Wouldn’t the Magnuson-Moss Warranty Act still apply?
The act is intended to allow voiding the warranty after modding the ECU (even though the act predates ECUs and so doesn't mention them). Well your radio warranty would probably still apply, but modding the ECU has potential to damage the engine, and therefore the engine is out of warranty if you touch the ECU code.
You're talking about the possibility of maybe eventually causing some kind of damage, but isn't the important question whether it caused the specific damage that the owner wants to be repaired under warranty?