One problem related to engine exhaust system has been reported for the 2008 Toyota Highlander. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2008 Toyota Highlander based on all problems reported for the 2008 Highlander.
Valve springs. While driving at 65 mph the vehicle stalled without warning. I managed to steer across 4 lanes of fast traffic to a complete stop. The car was towed to the closest Toyota dealer and was diagnosed as piston failure. The car was towed 140 miles to motorcars Toyota for repair. The technician inspected and diagnosed: "a valve spring on the #2 cylinder broke in front head and dropped into the # 2 cylinder, destroying the piston and severely damaging the short block assembly. Block had a hole in it and #2 piston was broken in half". Repair included: replacing short block assembly, front head, exhaust cam, valve, spring. I had to pay aprox. $6000 for a problem Toyota publicly admitted some 2008 v8 models had. Faulty valve springs was actually a recall but only for Lexus models. Not fair!.