before and after the catylitic converter.
you will fail the emissions test.
catylitic converter
one forward of the catylitic converter on the left side of exhaust, one aft. one forward of the catylitic converter on the right side of exhaust, one aft.
Cut it out and weld a new one in.
O2 sensors measure O2 levels in the exhaust so they are in the exhaust pipes. On newer vehicles there is 1 before the catylitic converter and another after to monitor the function of the converter. Pre obd2 vehicles usually have 1 sensor between the engine and the catylitic converter.
in the catylitic converter (underneath car...connected to your exhaust
Upstream is before the catylitic converter, downstrean is below the cat.
its under the car between the rear wheels. just behind the cab of the car
cut it off with sawsaw and weld a new one in. it also probably has a o2 sensor in it u need to remove it and reinstall it or replace it as well
Means you need a catylitic converter.
If engine is running well very possably the catylitic converter