Any tune that's not from the factory or CARB-approved will cause your car to fail a smog check starting next Monday. Go to "Smog Check Results" on the BAR Smog FAQ then scroll down to "My vehicle failed a Smog Check for having modified software. What can I do?"
https://www.bar.ca.gov/Consumer/Smog...-check-results
Up until the 19th, smog on modern cars (2000 and up) used to include just a visual inspection and a OBDII check that looks for check engine lights and that basic emissions equipment was functional. There also had to be a certain number of miles driven since the codes were cleared or ECU was flashed (drive cycle) in order to pass. That meant aftermarket tunes, while technically not allowed, would not cause a problem if the rest of the emissions equipment is still stock. Under the new procedure, the OBDII check will fail a car that has a non-approved tune too. Some smog shops are already doing the new check.
As for how this system will work, over the last 10 years the state has created a database for what various ECU values should be in specific cars. Additionally, the Calibration Verification Number (also called checksum) will be compared against what it should be for that car from the manufacturer. Checksums for CARB-legal tunes are whitelisted. It is very difficult, but not impossible, to tune a car without changing the checksum. Any aftermarket tune will change the checksum unless it was designed specifically not to.
https://tiremeetsroad.com/2021/07/13...led-smog-test/
I suspect this will be most relevant to N54 and N55 owners, because those cars have reached the age where they must be smogged and tunes are very popular. The earliest S55 and B58 cars will be reaching that age soon.
For many people this means that they will have to flash their car back to stock for at least one drive cycle before getting their smog check. It will be more of an issue for those with highly modified engines that may not run well or actually throw codes on a stock tune.
There are options for CARB-legal flashes, piggybacks, and engine parts for most BMWs but they often cost more than non-approved options. This new change in enforcement will likely make these offerings significantly more attractive.
In terms of shops who were already breaking the law and doing 'hot smogs', it remains to see if they will be able to get around this new system.
If we could please keep discussion completely off politics and have it focused on cars/BMWs I would appreciate it.