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.Google+
Car Problem Reports
Toyota Highlander Check Engine Light Due to Failed Oxygen Sensor Component
Toyota Highlander Problem
Average Mileage: 93,300 mi (50,000 mi - 150,000 mi)
Visitor, 2008 Toyota Highlander, 72,000 mi
Bad mileage noticed before the Check Engine light came on. Been on the shop off and on for 2 weeks. had all 4 sensors replaced. Car would barely go above 25 mph. Tons of hesitation. Horrible smell coming from engine area. (Mechanic says coolant) At the shop right now being fixed. Toyota MUST address this issue as it seems I have newer vehicle than some of you who have already posted and there is still a problem.
Visitor, 2003 Toyota Highlander, 90,000 mi
Car was not doing anything wrong. Check engine light came on. Took it to a shop. They changed the Mass Air Flow Sensor, for $300+. 24 hours later, check engine light comes on again. Take it back to the shop, figuring it has to do with the repair. They say, it's now the O2 Sensor. Car is still not acting funny, no way I'm going to pay anymore money. Took it so several shops since then, nobody can figure it out. Check engine light's been on 5 years now. Still doesn't act funny. Move to GA they require an emissions test, it fails for the O2 Sensor.
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.