California mandates standard diagnostic system for electric vehicles from MY26

The California Air Resources Board (CARB) has adopted requirements that bring electric vehicle diagnostic standardisation into line with internal combustion engine models, potentially setting a benchmark for the global automotive industry.

Because mandatory requirements for standardised diagnostic outputs were originally linked to tailpipe emissions control regulations they were never mandated for ZEVs.

Starting from the 2026 model year, all zero-emission vehicles (ZEV) sold in California must provide standardised data through diagnostic connectors that are accessible using existing scan tools and without the need for manufacturer-specific equipment, reducing the barriers to entry for repairing ZEVs.

Seven other states have already embraced the Advanced Clean Cars II program, making California’s regulation a potential blueprint for future nationwide and even global ZEV standards.

Making battery health status more easily accessible to consumers is central to policing a new mandatory battery warranty designed to provide consumers with confidence in the durability and reliability of ZEVs.

The mandatory warranty policy lasts eight years or 160,000km for vehicles in model years 2026-2030, covering any battery falling below 70 per cent of its original capacity, rising to 75 per cent from the 2031 model year.

However, there is a notable difference in approach between CARB and the United States federal Environmental Protection Agency, which automotive manufacturing association The Alliance for Automotive Innovation warns could increase complexity and costs for consumers compared with a harmonised global approach to EV regulations.