There are three on the 98. Two are located on the exhaust manifold basically beneath the passenger seat area. The other is on the manifold that goes to the drivers side of the engine and is located by the tranny pan.
A thread chaser. Your local auto parts store can sell you one.
The oxygen sensor for bank 1 sensor 1 for a 2000 mercury mountaineer is on the cylinder #1 side.
on the transmission
the O2 Sensor Should be on top of your exhaust manifold
Try replacing the upstream O2 sensor
The upstream O2 sensor is mounted in the ehxaust manifold The downstream O2 sensor is mounted in the exhaust pipe after the catalytic converter
The upstream O2 sensor is mounted in the ehxaust manifold The downstream O2 sensor is mounted in the exhaust pipe after the catalytic converter
unscrew it
Bank 2 is the drivers side of the engine in your Mercury Mountaineer Sensor 1 is between the engine and the catalytic converter ( upstream ) Sensor 2 is after the catalytic converter ( downstream )
On the exhaust pipe, lower, possibly near the catalytic converter.
It depends on which o2 sensor.
The upstream O2 sensor is mounted in the ehxaust manifold The downstream O2 sensor is mounted in the exhaust pipe after the catalytic converter