First of all, I've already tried to do my research and tried to get all the info I'm asking for myself (which obviously didn't work).

I want to know if CAN or OBD(-II) are in fact mandatory in the US and/or EU and where I can find proof for that.

I keep finding info on CAN being mandatory in the US since 2008 and 2001/2004 in the EU. However, I think people confuse CAN with OBD. It makes sense since you want a mandatory diagnostic interface and not just a protocol you could use. Obviously, I have no proof for that.

I've already found legal documents of the EU which suggest that OBD is in fact mandatory (http://eur-lex.europa.eu/resource.html?uri=cellar:9ee5d16b-1a4a-4a72-ac90-5e3a0bb1d745.0008.02/DOC_1&format=PDF). However, there is no statement about the start of this rule.

Can someone enlighten me in this case?

Thanks a lot :)

  • Is this a relevant question for maintenance and repair? Any vehicle owner prepared to purchase test equipment will be concerned about the results - not when or if it was legally mandated.
    – Solar Mike
    Commented Mar 23, 2017 at 14:52
  • I'm voting to close this question as off-topic because it is not about maintenance or repair - it might be interesting though...
    – Solar Mike
    Commented Mar 23, 2017 at 14:53
  • Because OBD and CAN are both potentially useful interfaces for maintenance and repair, knowing which are mandated to be present is useful for anyone contemplating equipment purchases for a home garage. Anyway, that's how I see it.
    – Edward
    Commented Mar 23, 2017 at 20:30
  • That is what your car workshop manual is for with the vin number to make sure you get the correct software / hardware. Knowing it was mandated in 1998 or 2001 or 2006 will not make it more correct than the manual and the vin...
    – Solar Mike
    Commented Mar 23, 2017 at 21:08
  • OBDII is an American specification. Check out EOBD for European cars.
    – anon
    Commented Apr 8, 2018 at 21:56

2 Answers 2


I believe you are confusing CAN and OBD.

CAN is an electronics interface protocol. Short for Controller Area Network, CAN allows for expandable interconnected systems, so you can add new sensors and actuators to a network with relative ease. It is comparable to SPI and I2C networking protocols. It makes sense that few automotive manufacturers would want to switch away from CAN because most OEMs that provide basic parts (ex. throttle bodies, OAT sensors, MAF sensors, ABS/ESP modules, etc.) use CAN protocol for the electronic interface.

OBD provides an interface for service. The OBD system is on the CAN bus, reads information from sensors, and provides relevant information in a user-parsable format (ex. CEL blink codes or modern universal error codes). It has a long history relating primarily to emissions control, which you can read about at your leisure, but the modern OBD-II specifications do in fact contain US federally-mandated measures. The EPA has a short Q&A on it that you might be interested to read.


To add to @Hari Genti answer.

He is exactly correct, CAN is the electrical interface, and OBD-II (On Board Diagnostics version 2) is about the connector and what pins are wired to what. There are a total of 5 different possible electrical interfaces defined for the OBD-II connectors. They are:

  • SAE J1850 PWM (Pulse Width Modulation)
  • SAE J1850 VPW (Variable Pulse Width)
  • ISO 9141-2
  • ISO 14230 KWP2000 (Keyword Protocol 2000)
  • ISO 15765 CAN (In either 250 or 500 kbit/s)

Typically only one is actually implemented for any given vehicle. But, more than one is allowed. However, all cars sold in the US as of 2008 are required to have CAN available at the OBD-II connector.

The protocol that defines the syntax of the bytes being transported by those protocols is SAE J1979. This is the standard that defines the modes, the PIDs, and the format of the data sent and received for each.

The OBD-II connector format was required for all US sold vehicles starting in 1996. This is why you're finding two dates. The connector pinout was required in 1996, and CAN was required to be populated in that connector starting in 2008.

All of this applies to the US. I don't have the info for other regions, but the source for all of this is:

Wikipedia Source

I hope that helps!

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