California to Test for Modified ECU Software During Smog Checks
July 16, 2021—The State of California will now check for modified engine control software during required biannual smog checks.
Beginning Monday, July 19, vehicles that have software not provided by an OEM or an approved California Air Resources Board aftermarket ECU will automatically fail the smog check, according to the State of California's website.
The crackdown on modified ECUs comes as California pushes to severely cut down on statewide carbon emissions. While not all ECUs result in a vehicle releasing higher levels of pollutants, the smog check does not have to prove that it does— the mere presence of unapproved ECUs is enough to fail the inspection.
Any driver whose vehicle fails a smog check, which is designed to identify unusually high levels of harmful pollutants in a vehicle, cannot renew their DMV registration without fixing the problem section of their car first.