I just purchased the Toyota Highlander 2003 and upon purchasing the vehicle I was very happy. The check engine light came on shortly after purchase and apparently the cause is a bad "ECM" board in the SUV. I am not sure if this is common but I have experienced this problem. I love the vehicle otherwise and plan on driving it for a while. Currently at 82K hope it lasts to 200K without major repairs.
2003 Toyota Highlander 2.4 L 4-cylinder engine, 108,000 miles, perfect service, until it developed coolant leak on the back side of the top of the engine, adjacent to an insulator pad at the back of the engine block. The back 3 head bolts were completely stripped, allowing coolant to leak into the engine. Toyota dealer says the short block or entire engine must be replaced, with no other option [$5200- $7400+.] Based on the frequency of identical engine failures, faulty factory assembly and/or design assures eventual failure of the engine. 25-year Toyota fan, probably lost forever.
We purchased this car new and kept it dealer maintained for 7 years. I found it to be quite a reliable vehicle until recently. At 118,000 miles it developed a coolant leak. It was ultimately found to be due to stripped out threads in the engine block (i.e. the car needed a new engine ~ $7500.00). After discovering that I was not the only one to experience this problem (check online Toyota forums), I notified Toyota. The Rep stated, "Your engine may be defective, but we cannot help you because you are out of warranty." Beware of the 4 cylinder engine in the 03 Highlander! A dealer maintained vehicle is worthless, and Toyota has lost a customer. And so it goes.
Purchased used 5 years ago with 86,000. Didn't flinch at the mileage due to Toyota's reputation for reliability; car drove well, at first. Sold at 109,000 due to expensive repair and maintainence costs including: All 4 wheel bearings, $500 a pop. Breaks completely replaced, some more than once. $2,000 spent on breaks in just 2 years. Evaporator sensor went bad; $400 just for the part. Muffler developed a small hole; $400 for a new one. Straw that broke the camel's back: drive shaft developed a wobble and needed complete replacement $1,200. Cut my losses and unloaded the hunk of junk. Other car was a 20 year old Subaru Legacy that had fewer problems and was cheaper to maintain.