Located in the middle underneath the car. Square looking with ridges. It'll have a pipe on either end connected.
The oxygen sensor on a 1999 Honda Civic is located on top of the catalytic converter. The catalytic converter is under the car.
There should be one in the header and one more in the catalytic converter.
Very carefully
The primary oxygen sensor is located before the catalytic on most Hondas depending on the year. If your Honda has the catalytic converter integrated to the exhaust manifold then you should find it on the manifold just before the catalytic converter.
There is one and it is before the catalytic converter.
No, it is illegal to remove a converter and besides the engine will not run right with the converter removed.
There is one before the catalytic converter where the 4 runners meet on the exhaust manifold. And the second one is after the catalytic converter.
probably the catalytic converter- or you child is smoking in the car
oxygen sensors are located just forward of your engine. In front of the engine is the catalytic converter. At the top at the bottom are your oxygen sensors.
After googling it is determined Code P0420 ( Catalytic converter effeciency below threshold)
Plugged air filter? Plugged fuel filter? Plugged catalytic converter?
Check the heat shield on the catalytic converter