not passing smog

there are dozens of sensors that could cause this. without knowing what was replaced, no one can help you. if you paid a shop for work and it still won't pass the smog test, i think they owe you an explanation!

If you failed the smog test because the readiness moniters have not run, then yes the technician is right. You will need to drive the vehicle a specific way meeting all of the parameters. Google it. But if you failed because you have current or pending codes, then those will need to be addressed first.