Currently, I'm working on an app which should show Gauge value (inHg) of the vehicle using OBD reader. Which values should I use to show the Gauge? Is there any formula?

  • "Gauge value" isn't specific enough since it could refer to multiple fluids. Are you talking about intake air, fuel or engine oil?
    – Zaid
    Commented Aug 28, 2018 at 8:56
  • @Zaid it should be air and fuel mixture Commented Aug 29, 2018 at 7:00

1 Answer 1


Gauge pressure (GP) is linked to absolute pressure (AP) by atmospheric pressure as in :

AP = GP + atmos p

Units can be Bar, Pascals, psi, mmH2O, inHg etc

But you can have them selected based on location ie Bar works well in Europe, psi in UK etc

  • Thank you for your answer, Do you have any idea OBD II ELM327 commands? Commented Jul 31, 2018 at 0:40

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