3 ms·

Do they still actually analyze the gas? When I did mine they just plugged into the computer and it was done in 10 seconds.

PaulHoule 2y ago
The point of https://en.wikipedia.org/wiki/On-board_diagnostics https://en.wikipedia.org/wiki/On-board_diagnostics is that the engine control unit in your car is monitoring the operation of the engine and thinks it is in spec. If the computer says it is OK, it is OK, at least in most states. For years there has been talk about an OBD-III that would use the cellular network or something so your car can narc on you if it is out of spec https://www.hotrod.com/features/obd-iii-the-proposed-future-of-on-board-biagnostics-982-1639-22-1/ https://www.hotrod.com/features/obd-iii-the-proposed-future-... This has been stuck in purgatory with all the other proposals for universal telematics not least because of privacy concerns plus cell phone carriers being uninterested in anything other than "what's convenient for us" coverage.
- ziddoap 2y ago
  >If the computer says it is OK, it is OK, at least in most states. The downside of this method (or upside, I guess, depending on where you stand), over the sniffer method, is that this is trivially bypassed. My race car, which is by no means emissions compliant, can pass this check with the press of a button.
  - Aurornis 2y ago
    States are beginning to roll out systems that do deeper checks on the firmware. Those, too, can be bypassed especially on older systems. However a lot of people are getting caught at emissions time now with cars that have been passing for years.
  - PaulHoule 2y ago
    Notably the functional test (measuring exhaust) can be gamed too, see https://en.wikipedia.org/wiki/Volkswagen_emissions_scandal https://en.wikipedia.org/wiki/Volkswagen_emissions_scandal Emission control is a balance between emissions, fuel economy and performance. You can give up some fuel economy and or performance at test time and enjoy better performance at the rest of the time if the system knows it is being tested.
    - deleted 2y ago
      [deleted]

PaulHoule 2y ago

The point of https://en.wikipedia.org/wiki/On-board_diagnostics https://en.wikipedia.org/wiki/On-board_diagnostics is that the engine control unit in your car is monitoring the operation of the engine and thinks it is in spec. If the computer says it is OK, it is OK, at least in most states. For years there has been talk about an OBD-III that would use the cellular network or something so your car can narc on you if it is out of spec https://www.hotrod.com/features/obd-iii-the-proposed-future-of-on-board-biagnostics-982-1639-22-1/ https://www.hotrod.com/features/obd-iii-the-proposed-future-... This has been stuck in purgatory with all the other proposals for universal telematics not least because of privacy concerns plus cell phone carriers being uninterested in anything other than "what's convenient for us" coverage.

ziddoap 2y ago
>If the computer says it is OK, it is OK, at least in most states. The downside of this method (or upside, I guess, depending on where you stand), over the sniffer method, is that this is trivially bypassed. My race car, which is by no means emissions compliant, can pass this check with the press of a button.
- Aurornis 2y ago
  States are beginning to roll out systems that do deeper checks on the firmware. Those, too, can be bypassed especially on older systems. However a lot of people are getting caught at emissions time now with cars that have been passing for years.
- PaulHoule 2y ago
  Notably the functional test (measuring exhaust) can be gamed too, see https://en.wikipedia.org/wiki/Volkswagen_emissions_scandal https://en.wikipedia.org/wiki/Volkswagen_emissions_scandal Emission control is a balance between emissions, fuel economy and performance. You can give up some fuel economy and or performance at test time and enjoy better performance at the rest of the time if the system knows it is being tested.
  - deleted 2y ago
    [deleted]