how to install a o2 sensor in the front bay in pontiac bonn.2003

Not terribly specific but you just need to disconnect the plug and use a special 02 sensor socket that has a slit in the side for the wires to stick out, or an open end wrench and take the old sensor out. Working on the backside of the engine is a little tricky due to the lack of space so you're most likely going to need a good size extension for your ratchet. Installation is pretty much the reverse, just make sure you use the antiseize/ dielectric grease thats most likely included with the new sensor on the threads and you're good to go.

Can I recommend putting PB blaster or another rust breaker around the threads on the Oxygen sensor for a few days in advance. That'll help it break loose easier.

Only if you also suggest cleaning up the residue completely aftwards so it doesn't get on the new sensor.