Where is the oxygen sensor on a 1990 Lexus es250?
on the exhaust
How do you change a knock sensor on a 1990 Lexus ES250 it has the same engine as a 1990 Toyota Camry?
You have to take the intake manifold off in order to do this. Both sensors (there are 2 of them) are on top of the heads. A dealer will typically charge $1100-$1500 for this service because it is time intensive. The sensors themselves are around $170 each. I would recommend a top end rebuild to get more value out of the time/money spent on this procedure.