You can try spray lube like PB Blaster, but if its badly rusted a torch to heat it up is usually the only thing that works.
it's in the down pipe coming from your exhaust manifold. you will have to remove the heat shield from the exhaust manifold to access it
The oxygen sensor is located in the exhaust manifold before the catalytic convertor. If you look down between the radiator and the exhaust manifold a few inches before the exhaust pipe connects to the exhaust manifold you will see the Oxygen sensor. The sensor will have 2 wires coming from it and it kinda looks like a sparkplug stuck into the exhaust manifold. There is 2 nuts that hold the oxygen sensor into the exhaust manifold.
By "exhaust manifold sensor" do you mean the O2 or oxygen sensor? The only sensor I know of on a exaust manifold is the O2 sensor and if you follow the manifold you will see 2 sensors sticking out they will have (usually) green wires coming from them
O2 sensor is located in the exhaust manifold just off the front of your motor. If you open the hood and locate your exhaust manifold, follow it down toward the radiator. you should see a 1-wire sensor sticking out of the exhaust manifold. this is your O2 sensor. you will need either a special Oxygen sensor removal tool, or a 7/8 wrench to remove it.
Screwed into the exhaust manifold.Screwed into the exhaust manifold.
In the exhaust manifold behind the engine.In the exhaust manifold behind the engine.
by unplugging the sensor from the contact and using a slotted socket to remove it. This socket usually is bought separate from a set.
In the exhaust manifold on the back of the engine.In the exhaust manifold on the back of the engine.
02 sensor is either in exhaust manifold, or in exhaust pipe between manifold and muffler
exhaust manifold
your oxygen sensor should be located on your exhaust manifold or on the exhaust pipe near the exhaust manifold, Make sure your engine is cool before placing your hands on the exhaust manifold, It can be very hot!
oxygen sensor is found either in exhaust manifold or in actual exhaust pipe between manifold and muffler