I am planning to inspect a 2012 Mercedes S550 for possible purchase.

How do I interrogate the electronic system of the car to get information about things that currently may not be working, or about problems the car may has had in the past? I have seen the computer dash of these cars and it is really complicated, so I am hoping someone with expertise can recommend the right procedure to investigate the electronics from the dash interface.

Note: I am not asking about using service computers. I am asking about information that can be determined solely by using the standard button interfaces from the driver's seat.

  • Google is your friend. Get a copy of the owner's manual, that should describe anything you can query without a special tool.
    – SteveRacer
    Mar 22, 2019 at 3:48
  • Star Diagnostics or Autel's 908 are both excellent for diagnosing MB.
    – narkeleptk
    Jan 24, 2020 at 0:24
  • The first question you ask is: What language do you speak ?
    – Alaska Man
    May 23, 2020 at 19:29

1 Answer 1


Note that anyone with a 15 buck bluetooth plug-in and an iPhone could already have reset the diagnostics, so you really need to take it for a spin & see if anything new comes up on a scanner.

It's very probably worth getting one for yourself; they work on multiple cars/manufacturers. Pretty much any car since about 1996 will have an ODB diagnostics plug. Codes are read out by the iPhone/Android app usually with some limited explanation which you will then have to further google. There are sites dedicated to ODB code explanations.

'Car Scanner ELM OBD2' is one such app - there are many but this one is often recommended by the ELM327 device makers [no affiliation with either]. Choosing OBDII Adapter gives some info & warnings on which ELM327 plug-ins to get or avoid.

  • These $15 plugs clear all modules or just engine?
    – narkeleptk
    Jan 24, 2020 at 0:22
  • They can clear all DTC codes & reset the MIL - they can get a vehicle out of limp-home mode, but of course not fix the actual problem.
    – Tetsujin
    Jan 24, 2020 at 7:29

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