Could you instruct a car thru the OBD port to open the trunk even if the car was turned off? Can you turn the accessories on from the port then open the trunk?

  • 3
    I suspect this is highly dependent on the make, model and year of the car @Bernie. Can you edit your question with these details? – GdD May 30 '18 at 13:53
  • So here is what I am thinking: If OnStar can pop the trunk on GM cars for Amazon, what if an ODB device could do the same universally? – Bernie May 30 '18 at 15:30
  • 1
    On Star has direct access to the body control module. which does not turn off with the key. – Moab May 30 '18 at 16:02

According to this response, when the ignition key is removed from the car it's usually not possible to communicate with the car via the OBD port so assuming by "turned off" you mean the ignition key removed, I'd say in most cases it is not possible.


The whole idea of the On Board Diagnostics port is to provide vehicle diagnostic information. It is read-only, except for specific log entries and specific fault codes that can be reset. It is not meant as a control interface for your car.

Also see Can i control the brakes of a car by the OBD II Interface?

  • Not entirely true for all cases. The Carly tool mycarly.com/product/bmw-app for BMW can reprogram many operations of the vehicle. Of course what's available in the BMW may not be pure "OBD." – mike65535 May 30 '18 at 15:59
  • 2
    Actually you can flash the ecm via the obd2 port, and likely a lot of other things by accessing pid's. Dealerships do it all the time solving problems. – Moab May 30 '18 at 16:00
  • And, every time you clear codes, the reader has to communicate with the ECU to do it ... that's not one way comms either. – Pᴀᴜʟsᴛᴇʀ2 May 30 '18 at 16:27
  • @Moab that often is done via another connector directly on the CAN bus instead of through the OBD port. But again, depends on manufacturer. – MadMarky May 30 '18 at 18:51
  • @Pᴀᴜʟsᴛᴇʀ2 just like i mentioned in my post, only some (not all) log entries and fault codes can be reset. Thats it. – MadMarky May 30 '18 at 18:51

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.