If the oxygen sensor won't break loose, try putting heat on the headpipe where the sensor screws in. If you have access to a acetylene torch, heat the pipe until it starts glowing red, and while it's hot, put the oxygen sensor socket over the sensor and use a breaker bar to work it loose. Be careful that you don't burn yourself though.
On a 2006 Cadillac DTS, the O2 sensors are located in two main areas: upstream (pre-catalytic converter) and downstream (post-catalytic converter). The upstream O2 sensors are positioned on the exhaust manifold, while the downstream sensors are located on the exhaust pipe after the catalytic converter. Typically, there are a total of four O2 sensors—two for each bank of the engine.
On a 1996 Cadillac STS, the O2 (oxygen) sensors are located in the exhaust system. There are typically two sensors: one upstream (pre-catalytic converter) and one downstream (post-catalytic converter) on each bank of the engine. The upstream sensor is usually found near the exhaust manifold, while the downstream sensor is located further along the exhaust pipe, after the catalytic converter.
upstream
Upstream - newspaper - was created in 1996.
downstream and upstream
The duration of Swimming Upstream is 3240.0 seconds.
The duration of Upstream - film - is 3600.0 seconds.
assembly upstream and downstream in ammetres
when a body moves against the flow, it is known as upstream flow
Swimming Upstream was created on 2003-02-27.
Upstream - film - was created on 1927-01-30.
Upstream Tracker was created on 2010-05-05.