There are four, two on each side, pre- and post- catalyst.
There are two oxygen sensors in a 1992 Mercury Grand Marquis. ON one the left bank of the y pipe and one on the right bank. Use caution when removing them. Often times they are seized in there and lots of damage can occur when trying to remove them. Let the car warm up alittle to ease with removal but be careful not to burn yourself.
There are four.
There are a total of ( 4 oxygen sensors ) according to the engine wiring schematic for the 1997 Mercury Mountaineer in my Haynes repair manual ( 2 oxygen sensors are " upstream " sensors used by the PCM to adjust the air / fuel ratio of the engine ) ( 2 oxygen sensors are " downstream " sensors / catalyst monitors )
Four
There are two.
There are two.
4
The 1996 Mercury Gran Marquis does not have a 318 V8. It has a 281 V8 (4.6 Liter). 318 is a Chrysler engine. O2 sensors are located screwed into the exhaust system. Start at the exhaust manifold and go backward and you will find them. The cost varies from site to site. Ask you local Auto Parts store for a price quote.
The oxygen sensors are in the exhaust pipes on most models.
4
FOUR
The 2003 Mercury Grand Marquis came equipped with the 4. 6L V8. Oxygen (O2) sensor locations are upstream and downstream (before and after the catalytic converters).