I believe you'll find it at the point where the exhaust pipe fits into the inlet of the catalytic converter.
The oxygen sensor on a 2004 Honda Accord is found on the exhaust system. They are placed close to the catalytic converter so the sensors can properly read the exhaust flow.
Depending on which sensor, IS it sensor 1 or 2
In the glove box
Honda oxygen sensor is usually positioned in the exhaust manifold downpipe before the catalytic converter of your Honda vehicle or in the middle of the two mentioned components. For more details: http://sites.google.com/site/hondarepairsite/home/2004-honda-oxygen-sensor
It's the one closet to the engine.
There are 2 oxygen sensors on my 2004. They are on the drivers side of the exhaust between the manifold and the catalytic converter. Put the vehicle up on ramps and duck under there and you will see them.
The oxygen sensor on a 2004 Volkswagen Jetta is located in the engine area. It is usually encouraged to warm up the engine so as to ease the threads.
It is on the throttle body just below the throttle linkage.
where is the oxygen sensor in a 2004 astro van
Idle Air Temperature sensor.
The roof
The 2004 Dodge Intrepid oxygen sensor can be found on the back of the air cleaner housing. Remove the wiring harness. Remove the oxygen sensor retaining screws. Reverse the process to install the new oxygen sensor.