One problem related to check engine light on has been reported for the 2001 Toyota Highlander. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2001 Toyota Highlander based on all problems reported for the 2001 Highlander.
Oxygen sensor failed (caused check engine light to go on), within 24 hours of having it replaced check engine light went on again and a second oxygen sensor had failed,which also had to be replaced. Check engine light is on again.