If your gas-powered car was manufactured after 1991, it is most likely equipped with a mandatory On Board Diagnostic (OBD) system – a computer that monitors the health of the engine and various other components, effectively functioning like a doctor for your car.
For electric cars, a standardized OBD system has been notably absent. Since EVs don't have traditional powertrain components, their systems, including batteries and electric motors require automakers and emissions control agencies to rethink how to provide uniform and accurate data to owners and service centers.
It seems like the authorities have taken this matter seriously. From 2026, California Air Resources Board's (CARB) Advanced Clean Cars II program would require automakers to equip their EVs with a standard diagnostic system, similar to the OBD II in ICE cars, a CARB spokesperson told InsideEVs.
"It's the same connector, same communications protocol, but it’s not OBD," said John Swanton, Air Pollution Specialist at the office of communications at CARB. "The important thing is that it will be a useful and familiar resource for both consumers and service providers."
"These requirements include a driver-accessible display of the battery’s state of health and charging speed and requirements to provide independent repair shops access to the same information and tooling as franchised dealer networks," Swanton added, highlighting the importance of uniform data accessibility.
However, these regulations are specific to California, at least as of now. Swanton said that "[the regulations] are informed by SAE standards, including J1979-3, that define standardized data services for zero-emission propulsion systems. These requirements only apply to California-certified new zero-emission vehicles (ZEVs) starting in the 2026 model year."
Title 13, section 1962.5 of the California Code of Regulations outlining the data standardization requirements states that 40 percent of a manufacturer's 2026 model year ZEVs and PHEVs need to meet this requirement. From 2027, 100 percent of ZEVs and PHEVs must have the standardized diagnostic connector.
Seven of the 17 states that follow California emissions rules have already adopted Advanced Clean Cars II regulations – so it’s possible that California could become the industry standard for the same, Automotive News speculated. The new rules cover the battery pack, power electronics, charging system, and thermal systems, according to the report.
When a traditional OBD system detects an issue in your gas car, it triggers a warning light on your car's gauge cluster, such as the check engine light for example, as a clear signal for you to get your car inspected. This not only alerts the driver but also assists service centers in promptly identifying and resolving the problem.
Cars, depending on where they’re manufactured, might follow the Environmental Protection Agency’s (EPA) OBD requirements, or California’s OBD II requirements. The Golden State’s regulations are also adopted by many other states.
As EV technology is expected to rapidly advance over the course of this decade and beyond, with new platforms and battery systems already under the works, creating a standard for such a fast-growing field can prove to be challenging, which is probably why we haven’t seen a standardized diagnostic system for EVs in the U.S. so far.
Yet, California's proactive stance in this regard may pave the way for an industry standard, and in time, offer EV owners a diagnostic system – hopefully as reliable and universal as the one their gasoline-powered counterparts have enjoyed for decades.