If they wanted you to have that info, the software that powers the code reader would already be in the cars computer and would show human readable errors.
They don't
this post was submitted on 20 Dec 2024
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Because FUCK YOU. That's why.
Car companies want you to go back to the dealership to have codes read. They had to be sued into releasing the code's meanings so independent shops and owners could do their own repairs.
Even though most car owners are knuckle draggers who don't understand oil changes or air filter changes, they don't want to make it any easier to do repairs outside of dealerships. I know someone who swears by dealerships and was very confused when I asked if he ever changed the air filter to improve fuel economy. For some reason, he thought his car didn't have one.
"Fuck you. Give us money" - BMW (probably)
They want you to go to the dealership...
The only reason you can read the codes at all is because of regulation... For now thanks Trump
Surprisingly, Teslas actually do. You have to access a hidden menu, but it's well documented and easy to do.
They don't want to maintain the software for it.
Also, they simply don't want you to know. Especially if the whole setup is already a patchwork of sensors that barely work together in the first place. It might cause unnecessary questions, concerns or even liabilities.
A lot of it is useless anyway as long as the car is not broken, and if it is broken, the sensor might be broken too. It's meant for diagnostics only.
They don't want to maintain the software for it.
That's fine, I just want the error codes displayed on the existing screens. No software necessary for that. Maybe a simple script at worst..
Also, they simply don't want you to know.
They want it to be known, otherwise there wouldn't be fail codes output to the OBDII port....
It's meant for diagnostics only.
Yes. Why don't they display diagnostics error codes on the existing displays? I'm fine with special display modes and "secret" menu options.
Who is going to look at that stuff apart from technicians? Most users have no clue how the functionality of their vehicle is achieved and they don't care.
For argument's sake, let's assume there is a userbase for this type of information. It would be possible to show diagnostic information like DTC or run DID routines from the dashboard but this is already possible from any cheap offboard tester, via a phone app or laptop.
The reality is that even if an OEM wanted to provide detailed diagnostic information, they don't know it either because the information isn't disclosed by their supply chain. Companies such as Bosch, who supply brake ECU, are extremely tight lipped about their intellectual property. When something goes wrong we use a special development version of the ECU to record the associated software variables during the fault and present that as evidence but we don't have access to the source code.
Modern products are not designed to be repaired. They want us to continually buy new shit. Basically anything with software in it is an absolute nightmare to maintain. It makes me depressed just thinking about what a clusterfuck this landscape is.
Source: control system engineer for a large OEM.
I mean, I don't think they're taking about a full diagnostic. Just the code associated with a CEL.
It'd be nice if you could read the code from the dashboard or infotainment without digging out a code reader.
And it'd be even better if they had human readable descriptions for those codes, especially for OEM specific codes.
For most people, a CEL is all you really need. But sometimes and for some people, just telling them the problem would be super helpful.
For example, a loose gas cap is a CEL. Save people $100 at the mechanic if it was just like "check that your gas cap is tight"
Who is going to look at that stuff apart from technicians?
Anyone who owns expensive equipment and is serious about true ownership including all possible maintenance and repairs. Hi, I'm the guy who would be looking at it if it was visible without shitty dongles or 5-figure ASICs.
Tell your employer they could have share prices doing numbers if they did the slightest bit of QOL improvements for anyone remotely like me.
Hell cars have flash codes. I used to have a Holden commodore bridge out two pins in the obd connector and it would flash codes on the check engine light.
I'm sure cars can still achieve this easily enough.
But again useless information to the masses. I'm a crane technician and used to work for a large OEM and even we we pulled DTC codes down often they were little to no help
The same reason they won't let you buy the dealership scan software for under 10k. Almost every maker has an in house scanner and due to standards they only need to provide certain data to non dealer level tools and I believe the standard only exists for gas powered vehicles that need to provide OBD2 data. Plenty of makers (BMW is horrible about this) stuff away data where a normal obd scanner just won't access and it's gotten much worse with the overuse of CANBus (I sure love when my trunk lid sensor prevents my fucking car from starting).
Thats where your snapon and other third party scanners start bringing a gap, but even those are extremely pricey and need to be updated constantly and even those usually won't do EVERYTHING.
Fwiw the cheapest and best way I've found is basically to pirate the dealer software and get a compatible knockoff scanner (vxdiag for example). I have Ford IDS and a couple others this way but assume that the software is gonna install something malicious and dedicate an old Thinkpad or something to it.
Depending on the age of your vehicle something like Torque Pro is extremely useful. I have mine monitoring transmission temp, long and short term fuel trims, O2 sensor signals, voltage, mass air speed, intake temp. It's more than enough data to see something coming long before it becomes an issue.
If you have a Ford, there's free software called Forscan that will perform all of the duties of the dealer service software. I used it when I replaced my wife's ABS module on her Edge. You can even use it to program keys and modify things.
Yep FORScan let me set the VIN on an electronic power steering rack (because that's totally cool to require so you can't just replace it at home right?).
I beleive it is actually IDS just reverse engineered and more accessible, unfortunately not every maker has one of those out there it really should be legally required when you buy the car to at least get the software to "own" it.
Yeah I was so psyched when I came across it while trying to diagnose the ABS issue. I searched for something similar for Toyota and Chevy for our other cars but was bummed that nothing like it exists for either one.
We could have had readable diagnostics since they started showing multiple items on the in-dash LCDs. It's always money.
Even OBD1 cars had that in the form of a blinking check engine light.
Shit, it works for my furnace 😅
Our 85 Thunderbird used to blink a set of numbers out. But you still had to have some type of information to make use of it
As someone pointed out on the comment, one of the reason is Money, the other one is safety and security ~~based on Vehicle manufacturer claim~~.
Yet, nobody can stop you to sniff and monitor your own car CAN/OBD2 interface using as simple as cheap microcontroller and compatible OBD2 interface kit (e.g CAN Transceiver/Controller kit).
EDIT: So far this curated list helpful to me for CAN bus based protocol.
As other mentioned cheap ODB2 readers, but some brands offer a lot of diagnostic data over the infotainment system, they just won't display them to you - for BMW I use AAIdrive (is foss, github/AAIdrive) and it displays some of the data on the main screen without a physical ODB2 reader inserted.
(And ofc custom navigation, VLC, etc)
I am going to spend my holiday break looking into this, thank you very much!
I’m not aware of any car manufacturers selling their own diagnostic ASICs, so it’s not an extra margin to squeeze afaik…
What? The errors are intentionally vague so the drivers are forced to go to a dealer, giving them a chance to lie and pretend that's something very serious and very expensive, while all they're going to do is a reseat of a cable and a error reset
Btw Car scanner supports showing obd data on Android auto. It's a game changer for hypermilers
I disagree... Error codes from the OBD port are usually system-specific. They make troubleshooting very easy if you use online resources... I just want a quick readout on the included hardware.
Not a fan of dongles and such. I own a few different 'Amazon specials' and the UI feels like hot garbage (given I use them maybe 1-2x a year at most).
I think it's more that the protocol is universal across the industry even though engines are all built somewhat differently, so you can only have a generic code to tell you what's wrong.
The name sounds like my phone is going to wake up in a bathtub full of ice and missing a camera module, but Car Scanner is legit.
The sad answer is that those displays exist to cut costs, not to make your ownership experience better.
Also the dealers want you to come to them for that CEL, and the companies don’t want to piss off the dealers.
They make the ownership experience worse. I fucking hate mine.
I wish I could replace half of the real estate with buttons and.knobs but nooooo, I can't afford a car with such fancy craftsmanship so it's a cheap shitty screen with a cheap shitty OS instead. And everyone things it's fancy...LOL
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Just to throw this out there, but car dealership owners are close to the scummiest people on the planet.
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What I've learned with 15 years in the DIY repair sphere is that (obviously to me) the codes don't tell you what's at fault, only what's not reading correctly and (to my surprise) the general public will just replace what the code says is off. A MAF code doesn't tell you if it's the sensor, the wiring, or the PCM.
While I'd certainly appreciate a simple code readout because I'm pretty knowledgeable about which are actually concerning this moment vs this year vs never, diagnosis typically takes more equipment and time. The cost and hassle of the reader is negligible in the repair. I use a Bluetooth dongle and Torque app to read all kinds of stats when diagnosing. An integrated interface would be convenient in some ways, but the portability of a phone/tablet probably has an equal amount of convenience once hard diag is needed
They probably don't want YOU to be the one diagnosing.
There is a standard connector which existed before big screens landed in cars, the OBD2 connector. Dongles are cheap and you can read the output from your phone or computer. Some dongles support bluetooth. The connector is mandated in some markets and I guess that makes it less interesting to add a redundant interface inside of the car. It's fun to try if you're interested. Manufacturers can extend the error codes IIRC.
Tesla has a service mode on the display through which you can scan the car for faults, run a battery test, ... It is password protected but the password is publicly available.
Interesting fact. OBDII is a CARB requirement, so it’s tied to cars that must meet emissions standards. This is why Teslas don’t need to include one (ands it likely other manufacturers will stop including them in their electric models at some point as well). No emissions systems to check means no need for an OBDII port.
Usually I wouldn't be that guy, but it's OBD2, not ODB2.
OBD - On Board Diagnostics
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Bingo! You can get a BT adapter for $7 on eBay. Torque is the absolute killer app. I'm stunned something so complete and customizable is free, a few bucks for the full version. I suck at mechanics, but that has saved my butt a time or two.
If you own a car that was made in the last several decades, it has the OBDII connector under the steering wheel and openly accessible. You just plug the adapter in and connect to your phone. The adapter and app are every bit as important to me as a jack, lug wrench and tire pump. No one should be without for a measly $20.
My wife's car occasionally throws an error that kills the cruise control. She can clear the error code while I'm driving! If you have ever had a mysterious check engine light, you can see exactly what it means.
Torque is ancient and not supported on current versions of Android.
I've been using Piston for a long time and I've been happy with it
Yeah that's what it said for me when I clicked that playstore link. Apparently my 4 year old phone is too new to use the app.
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They want you going to the dealer, so they can upsell more maintenance and repair costs.
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