The Check Engine Light may illuminate because a component of the oxygen sensor stops working. As a result the engine computer is unable to determine the proper ratio of air to fuel for the engine. Replacing the failed oxygen sensor should correct this concern.
Car Problem Reports
Toyota Highlander Check Engine Light Due to Failed Oxygen Sensor Component
Toyota Highlander Problem
Average Mileage: 88,714 mi (50,000 mi - 135,000 mi)
Visitor, 2002 Toyota Highlander, 89,000 mi
when humid or rainy it misses I put it on a diagnoses at auto zone they reported it to be the oxygen sencor #2
The CE light was on and my gas mileage was awful. I got the part replaced. The CE light turned off, but my gas mileage only improved a little.
I had two of these go and the mechanic said they are common on Highlanders.
Visitor, 2001 Toyota Highlander, 117,000 mi
Have literally taken this in to be dealt with 4 times without resolution. Check engine and VSC still come on until we started ignoring it.