Using an OBD Device When Purchasing a Used Car-Is This Ethical?

Greetings OBers! At sometime in the future I will be buying a secondhand vehicle ( actually, a Toyota Hilux which I will be purchasing secondhand in Chile, but this question applies to buying it anywhere).

Anyway I would appreciate your comments on this idea. I have an OBD-II module which plugs into the OBD port of any car that has one. I communicate with the module via Wi-Fi on my smartphone. The purpose of doing this is to check if the car has any current known issues. I think through this connector it is also possible to check history, i.e. what faults it has had in the past and which error codes has been cleared and when. All of this provides additional information on the state of the vehicle to see if I should purchase it or not.

I think this approach could be done either on a private purchase or even through a dealer. My philosophy would be that if the owner objects to me plugging in my device to check the vehicle status, then I would assume that he has something to hide and I will walk away.

Apart from any error codes that are reported is there anything else that I should check with the OBD device. Obviously, I realise that this does not replace the standard or normal checks that one should make when buying a used vehicle. It is just supplementary or additional information.

Your advice and comments are appreciated.

Comments

  • +4

    As far as I am concerned, when buying a car I am entitled to take all the precautions available to me, be it a mechanical check or electronics using an OBD device.
    I am not sure about the ability to check past history insofar as what fault codes have been recorded and corrected/erased, but you will be able to see what warning lights on the dash have been inactivated to hide current issues.
    From experience, the more expensive the OBD reader then the wider the range of error codes and other readings that will be available.

  • a Toyota Hilux which I will be purchasing secondhand in Chile

    And getting it complied here? Or is it a personal vehicle that you've owned for a year already? The Hilux is not on the SEVS list…

    • No, no! I will be buying it in Chile for exclusive use in Chile and South America. When I retire next year we will be living in Chile for 2-3 months per year and I needed a vehicle over there. I want a 4x4 turbo diesel, as these perform much better at extremely high altitude driving which we will be doing (over 5000m!!). So much amazing places to go there in the high Atacama desert etc!!

      • Aha! That makes much more sense! :)

        • Ta!

  • +2

    Totally ethical, but most of the time totally pointless. Unless there is a light on the dash, there is a good chance that codes have either been deleted or never occurred. There may be some long term codes stored, but it isn't conclusive as it doesn't usually have time or date. Not many vehicles keep deleted codes, let alone when they were deleted. The EEPROM used in most cars holds very little information and most of the time it's up to the OBD reader to decipher what info the car is feeding it

    Another thing is that OBD only covers engine management and not many cheap Chinese made readers will do SRS or ABS systems.

    Basically, no problem doing it, but you need to know what you are looking for, what that reader and car support and what you plan on doing with the information.

    One thing you might want to check is that the ECU, if it supports it, that the KM traveled matches what is displayed on the dash. Some vehicles this can't be different, but some, it can.

    Source: ex dealer mechanic for 20 or so years. Lots of experience with OBD systems.

    • Good advice, thank you! I was not aware that the ECU can report via OBD the number of kilometres that the vehicle has travelled which can be compared with the odometer reading. It appears that chile is a little bit behind the rest of the world. I found out that diesel cars in Chile were only mandated to have OBD connectors after January 2013 much later than Australia for example. But I was planning on buying a used vehicle not more than 3-4 years anyway!!
      https://files.ozbargain.com.au/upload/150847/52324/img_6029.…

  • +5

    If I was selling my car and someone asked if they can plug in some cheap Chinese adaptor into my cars computer port, I would probably say no. If they had a high quality (like mechanic shop gear) I would be fine with it. I don't need some crappy gear potentially frying my computer, and yes it can happen.

    While it sounds a bit hypocritical, I myself own a Chinese Tech2 clone for my VY commodore, but I knew the risks of the Chinese clones and their build quality when I bought it, and it was my car and my risk to take. One time I plugged it in and straight away my car lost all power and it wouldn't start. Warning light was going off, and dash lights were flashing, freaked me the hell out. Turns out that one of threaded tubes (??? that you screw the cable into so it doesn't come loose, like your computer video cable), had come off and had shorted the circuit board, when then shorted my ECU and popped the fuse. Thankfully it was only a fuse and no damage to the car or the Tech2, but it could easily have been. So that's why I wouldn't let someone start plugging shit into my car.

    • Fair enough comment. But probably in this case, I would just move on to the next potential vehicle to purchase. Anyway, I wasn't planning on using some "cheap Chinese sh*t" OBD device. I was planning on getting this ( http://www.obdlink.com/mxwf/ ) "quality" one which has had good reviews and performance!

      • +3

        I wouldn't let any random person do that to my car either, but say you get a NRMA inspector doing it, I would probably allow it. It's as much the equipment as the person who's doing it.

      • And I as a seller would understand that that is your choice to make, just as I would hope that you as the buyer would understand that me not allowing it is my choice.

        Now if the buyer had asked me if they can do it when they arranged the inspection time, I might actually consider it. Because I would research the model scanner they were bringing. Or if the scanner was operated my an RACQ or similar car inspector or mechanic, I would be fine with it.

        Also you would need to be sure that the scanner you bring would actually be able to pull codes from the vehicle you are looking at. My VY V6 Commodore for example, has an OBDII plug, but uses ALDL protocols. And even if you had the tool to speak the right language, do you have that manufacturers codes stored on the device? Without it the tool will tell you this code, but you don't know what that mean. My Commodore would display code 12, you might think that is a fault, but it just means no faults. There is a reason that mechanics pay many thousands of dollars for their scan tools, because they need to buy all the relevant data too.

    • +5

      Yeah I wouldn't let a random twat off the street plug random shit into my car.

      • +2

        Agreed, someone would be welcome to make all the visual inspections they like, but I would not have a random punter plugging stuff in and out or doing anything else physical to the car (any form of removing items to make inspections/get to other items, etc.).

        If they had a qualified, professional person (e.g. NRMA) out to do the job then fair enough, but random punters who could easily cause some sort of damage and then just walk away with nothing more than a "sorry mate"? No thanks!

    • +1

      Agree with all the above :) No way are you plugging something you claim as a 'reader' into the diagnostics port. How do I know you're just reading codes, and not screwing up the settings? Hell to the no.

      • +1

        Omg! They could clear the long term fuel trim. I spent thousands of km setting those up…

        Have to say, there isnt a lot you can do with most OBD readers other than read the codes. Clear some codes, maybe. Reset fuel trims, maybe. Most ECU setting changes need to be made via firmware updates or with special software.

        Would I let someone connect an OBD reader to my car? Probably. I would enquire as to why and what they are looking for if there was no error lights up on the dash. Or I would offer to use my own and show them.

        An OBD reader is not some mythical be all to end all unicorn device. Most people that have them don't even know the full extent of what they can do with it or what 90% of the information is or how to interpret it.

        But, like most have said, I would be asking why and what are you hoping to seek from plugging it in. If there are no lights, chances are, there are no codes, or the only code it finds (like Ados said above) is "code 12" that means… ironically, no codes found… :D

  • +1

    I have a dodgy O2 sensor in my car and the engine light comes on regularly. After checking the error message, I use a bluetooth dongle to clear it. I want the spurious error cleared so that if something serious does get reported by the computer, I can see the engine light come on and can check it out. To my knowledge when I clear it, I clear the entire 'error' history.

  • Someone I knew many years ago took a jar of used engine oil to car auctions and poured some on any vehicle he was interested in buying. I seem to recall if he had the opportunity he did something to the distributor - water, change advance or gap?

    Could you do anything with an ODB dongle to mess up the car and reduce the price?

    However, sometimes people will buy no matter how bad the vehicle looks or runs. I sold a 17 year old car that had been sitting in a friend's garage for 6 months. I drove it home 1km to our place and it ran fine. When I took the first prospective buyer for a test drive it coughed and spluttered. He bought it anyway for the asking price.

    It's always a worry when someone accepts your asking price. You suspect you may have under priced.

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