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For passenger cars in the US, the OBD2 interface has been mandated for many years. The interface allows you to query a lot of car data from the computer using a scanner tool. The OBD2 system also sets "trouble codes" if something goes wrong with the car so that you can diagnose the problem. In most jurisdictions that do car inspections, you are not allowed to have any active trouble codes on the OBD2 interface in order to pass the inspection. This depends on the specific locality and their inspection rules.

Do electric cars have OBD2 interfaces on them, and how do they differ from those on gasoline cars? Do they still allow access to car data, and what kind of data is usually exposed (battery level, battery temperature, etc.)? Furthermore, do electric cars set "trouble codes" the same way, and could they theoretically fail an emissions inspection if they had active trouble codes?

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  • Which electric car are you referring to? I don't believe there is a standard answer for all. It's my understanding that some do and some do not. Tesla, for example, does not and uses a proprietary connector and protocol.
    – jwh20
    Jan 31, 2022 at 19:05
  • In case Tesla does not have an OBD2 interface, how does one pass an emissions test in a jurisdiction that requires OBD2 interface? Do all jurisdictions have special rules for electric cars?
    – BetterSense
    Jan 31, 2022 at 19:08
  • Good question. Another problem is how will they insert the exhaust gas sensor? My assumption would be that those states where emission tests are required have a procedure or exemption for electric vehicles.
    – jwh20
    Jan 31, 2022 at 19:17
  • I would bet EVs have special handling when it comes to emissions. Just like in some places, cars past a certain date no longer need to pass emissions (which seems stupid to me, lol), EVs are probably coded out where they don't need to be tested (for obvious reasons) to get registered/licensed. The overall question here is a good one and something I'd not thought of ... so good on yah! :o)
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Jan 31, 2022 at 19:23

2 Answers 2

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The Nissan Leaf (all model years) has a standard OBD-II port. It's typically used in combination with Leaf Spy Pro to learn

The Kia Soul EV also has a standard OBD-II port. There's a forum thread showing where to find it.

I would assume that most EVs from major established auto manufacturers still have OBD-II ports because that's what technicians and mechanics are familiar with using.

(Sorry for the partial answer; that's all I know.)

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  • I would suggest you're spot on. The OBDII port is used for a lot more than just emissions. It's the port by which the car talks to the mechanic and tells them what's going on (or at least, can indicate what's going on). I'm pretty sure EVs aren't a perfect vehicle and will have problems not unlike their ICE powered brethren. I would bet all EVs have OBDII ports and will continue to use them until a new standard is laid out.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Jan 31, 2022 at 22:54
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This depends on the vehicle. EVs that are based on the electronic platform of current ICE vehicles are using conventional OBD2 standard. This is valid for cars like VW e-Golf. Those vehicles can have brand-specific messages that can be decoded with a proprietary diagnostics system (including those ones that are specific to the electric powertrain). Those parameters are monitored, stored, and processed on ECUs that are responsible for a specific part of the system (such as for example DC/AC or DC/DC converter, electric powertrain controller, battery monitor control unit).

Most of the vehicles use both the OBD2 connector and ISO 15765 protocol for communication. The drawback of this is that standardized diagnostic code readers have implemented codes that will not be utilized in the EV (such as the P01XX group for fueling). On the other hand, EVs are dependent on other parameters such as SoC (State of Charge), cell temperature, cell heating, or cooling status, which were not an aim during the initial onboard diagnostics system design.

There are vehicles like Tesla which use solutions that are specific to their own brand. As far as I know, some Tesla vehicles (like Model 3) use adapters that can convert to OBD2 connector. This is an interesting topic, as according to EU legislation, M1 category passenger vehicles needs to be equipped with EOBD standard. EOBD standard is vastly similar to OBD2. Petrol cars registered after 01.01.2001 and Diesel powered vehicles registered after 01.01.2004 need to comply to get EU homologation. I believe that during this legislation electric vehicles were not included, therefore this may not apply (I need to investigate it more. I am not fully sure about this one).

Also worth noting is the fact that EV exchanges information about some of the mentioned above parameters with charging station. This information are crucial to safe and effective charging. A good source of information regarding this can be found on Open Charge Alliance. For more information please visit: Open Charge Alliance

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  • "NY State has two types of inspections, $15 and the other is $35 and includes a full emission check. The Tesla only needs the safety inspection and it should be $15." Teslas with zero emissions don't need OBDII however, Teslas do have an OBD II port (ohptools.com/blogs/news/…) OBDII is mainly ice vehicles emissions control systems.
    – F Dryer
    Feb 5, 2022 at 18:55

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