They still don't have a diagnosis of what's wrong with the car. They've been told about a whole bunch of things going wrong, including battery-related stuff (which is probably why the car was prevented from driving further!). At least it does seem to be an exceptional case, I'm pretty sure we would know if it wasn't.
So, yes, car manufacturers do exactly this right now. But if you want exact details, or if you have an older MY car you can plug in your own odb-ii reader and download one of the many apps to get those details.
My car just threw a CEL and it was because I put low octane gas in. I knew this but also found this by using the handy Forscan app
I put 60,000 miles on a Jeep with a check engine light. Also spent thousands on trying to fix it at various shops which would replace all sorts of things, to no effect, including about 5 attempts to replace a costly computer board.
Eventually had a redneck guy working out of the back of his pickup truck have a go at it. After hearing about the history he spent hours unplugging, cleaning, and replugging every single wire connection and socket. And the light stayed off.
It's a good idea, but such a ruse would be easy to catch. A properly-wired check engine light illuminates whenever accessory power is on and the engine isn't running: i.e., right before you start the car, every time you start the car.
The check engine light is only for emissions related failures which is why in most cases the car is still driveable. In serious cases like this most cars will flash the CEL but AFAIK that is not legally required. The whole point of the CEL is that when the emission system is compromised its not immediately obvious, in fact the car may even perform better depending on the fault.
So just a nitpick, but the CEL is not exclusively for emissions related codes. There are a wide range of things that can fail that do not affect the emissions output of the car, but will still trigger a code and light. All of them can fail you in an emissions test, but not all of them are emissions related.
Edit: All of them will fail you -> All of them can fail you. Not all codes will trigger an immediate fail in CA smog testing anyways, depending on if they are manufacturer specific, or what they effect. I passed my most recent smog with a few codes.
Which people drive around with for weeks without care because it usually feels like a light that indicates the dealer would love to extract some exorbitant service fee from you light.
True, though some cars fall into “limp mode” making it challenging to drive very far. That typically limits the max RPM if a potential catastrophic drivetrain issue is detected while not also stranding you.
I don’t think that’s true, though it may depend on the make and model - the related service manual should be consulted. Limp mode is intentional and is mostly meant to limit function while sensors may be disabled, compromised or uncertain. There’s a sensitivity to drivetrain timing that narrows as RPMs increase (e.g. approach redline), limp mode seems to mostly use sane defaults for everything to avoid catastrophic failure in that type of scenario.
