Q: OBD-II failed for smog check

Unfortunately without more information as to why your Toyota Corolla did not pass the emissions test, it is difficult to determine the cause for the failed smog check. Provided that the ODB2 port itself has power and is allowing the emissions tester to read the computer, we would need to know what codes the computer populated in order to determine where to investigate necessary repairs. Typically, if you have active codes in the vehicle’s computer, then the Check Engine Light will also be illuminated. This is the first indication that a vehicle will not pass smog. If this is the case for your Corolla, I highly recommend that the next time your emissions test is due, observe the status of this light if it is on and enlist the help of a certified mechanic to help you troubleshoot the codes. Not only will they diagnose and repair the problem, they can aide in informing you if your Toyota is ready to be smog tested. This will help you avoid wasting time before smog checks.