I was replacing a damaged oxygen sensor on the exhaust manifold when, as my luck would have it, the sensor broke off in the wrench leaving the threaded part still in the manifold. Is this drivable? I have to be somewhere in the next couple of days and don't have time to take it to a shop or re-drill the header. Any ideas? Furthermore, there's a hole in the header now that leaks exhaust. Bad? Or is their a way to patch it until I need to smog it?