Beware of the dreaded code stating leakage in exhaust system, for this is an idication of the head gasket going and leaking coolant. Upon further review it is found thatrear head bolts are stripped due to excessive heat most like caused by foam insulator pad between plastic intake manifold and engine.
Some say engine is toast, but the fix rec. is a time sert insert kit (approx $500 helicoil) with drill guide.
Mine is to be currently repaired at about a total cost of $2,900.00 as long as the helicoil kit holds the head bolt torque, we will see?
It is a design flaw in my opinion as it seems to be a regular issue with the four cylinder Highlanders approx.2001-2005? Failure was at 160,000 mi.
My car is in the shop (5/2/12) for this exact same problem at 160,000 miles.
I noticed a small reddish-brown puddle in my garage, so I took the car in.
They first thought it was the head gasket and then they discovered the stripped bolts.
I decided to get a new engine rather than donate the car, as the mechanic presented as an option. This is a very expensive problem that I never expected from a Toyota at this mileage.