The Oxygen Sensors play a significant role in lowering your 2001 Pontiac Firebird's emission results.
Depending on which emission (HC, CO, or NOx) caused your Pontiac to fail the smog check and whether or not the person who suggested replacing the EGR, O2, and Gas Cap did so after ensuring these components were defective, will determine if your Firebird can pass the smog check with the repairs you've made so far.
We can only suggest either replacing the correct oxygen sensor, or perhaps taking a chance at another smog test... hopefully with passing results.
posted by SmogTips Support