I'm not sure about 40% but it WILL reduce gas mileage I'm not sure about 40% but it will for sure reduce your gas mileage. 40% does extremely high for just one O2 sensor
You replace it when it has failed.
21.6
It could, if the old gasket had failed.
If the rest of the cluster is functioning properly, the cluster has failed.
Depends on the mileage on the vehicle which you failed to list.
Has the South African Bank failed in keeping inflation within the range of 3 to 6 percent? Discuss
80 percent would be an A and 38 percent you failed so the grade dont really matter
A properly working cat, no. Removing it, no. A failed cat, yes.A properly working cat, no. Removing it, no. A failed cat, yes.
The communication system for the computers has failed.
Some do and some don't . You failed to list what model Toyota and what engine, so I cannot answer your question.
Depends on what year you are referring to which you failed to list.
Usually the cluster has failed. You will need a new one, or a used one that has the same mileage showing.