You have the tuner in hand? Did he charge you for the tune and do you know what tuner he used?
I'd risk it from what I've seen since they changed the law in CA. Mostly the look at CEL and pass it. I say worth the risk and I wouldnt mention it to the tester. I would test it at a shop and not a smog only center if it were me.. No kidding my shop turns my truck on and starts it and looks for CEL and within 5 minutes I have smog check done. Since they changed the rules on how smog centers communicate with govt, it is fairly easy pass.
Smog Check Criteria for Transmissions
- No Tailpipe/Sniffer Test for Transmission: Smog checks for 2000 and newer OBD-II vehicles are primarily computer-based. The smog technician will not physically test or evaluate the internals of your transmission. [1]
- The "Check Engine Light" Rule: The only time a transmission issue will fail a California smog check is if it is throwing a Diagnostic Trouble Code (DTC) that illuminates the Check Engine Light. If there is no light, you are clear. [1, 2, 3]
- No Emissions Impact: Mechanical transmission parts (including heavy-duty or modified torque converters and modified valve bodies) do not alter the vehicle's exhaust emissions, so they do not require a CARB Executive Order (EO) exemption number. [1, 2]
Important CA Smog Warning
- Beware of Tuners: Upgraded transmissions often require aftermarket tuning (such as a custom TCM tune). While replacing the transmission itself will pass, running an untuned "delete" or non-CARB compliant engine/transmission tune will cause a smog failure. You must ensure any tuning maps are flashed back to stock for the test
