Which parts fail
Components named in complaints (engine, cooling system, oil leaks, timing chain, exhaust).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2003 Toyota Highlander owners, lightly cleaned up (personal details are redacted by NHTSA).
Automatically disengage the transmission Stopped the road Icalled my husband Myhusband came and together we got the car to a safe place.Then Icame home with my husband and he called the insurance company and had the car towed. Ifound a place to fix the car and they said the transmission was broken and it cost about 6500 dollars.Icontacted the insurance company said they couldn't help.The car was towed home and is not available.
The engine overheated suddenly, blowing hot air from the ac and the temperature gauge went up. We managed to get home and get to the Toyota dealership the next day. The dealership mechanic told us the engine bolts stripped due to the block being soft, and that he had seen this problem before. The issue of the soft block was confirmed in a subsequent search of the internet. Apparently Toyota is aware of this flaw, but there is no warranty remedy. The 2003 inline 4-cylinder engine is the model with the bolt stripping problem. Neither the dealership nor another japanese auto repair place would consider trying to replace the bolts. They said that because of the soft metal in the block, a new set of larger bored bolts would be unlikely to hold. The cost to put in another engine is approximately the value of the car, if there were used engines available. …
2003 Toyota Highlander 4 cyl. Service bulliton from them #310436. Head bolts coming undone inside motor causing catastrophic failure of motor. Bolts not holding down mfgr knows about this. Was a manufacturing process that did not work. On carcomplaints.com this is a rampant problem reported. Reads almost like a play book on how the motor overheats and fails, told headgasket, after opening up the motor it is found that the head bolts backed out. Toyota is normally a great car. I still owe money on this car and Toyota is basically not taking care of their customers and leaving us out to dry. Please issue a recall on this. Vehicle was driving and quickly overheated. This happened twice in a short distance. Easily can leave one stranded. No steam out the tailpipe and water gushed out side of motor. Dealer left motor apart when I went to pick it up after being dragged about. …
Needed to have a total engine rebuild due to faulty head bolts that stripped and allowed coolant to enter the engine and burn. Lucky-I guess-that I acted quickly so as to avert catalytic converter issues or sensors getting damaged by burning coolant. I also avoided the total loss of antifreeze and the resulting damage &/or inconvenience that thousands of others had. Still, a huge inconvenience and huge $5425.82 cost due to manufacturer's defect: weak metal that couldn't withstand the torque/pull on them... Perhaps the threading played a part. I only know that 1000s upon 1000s of people suffered the same issue from Toyota on this engine in several years/models. There should be a recall. There should be compensation.
Check engine light went on the morning of February 23, 2015. White smoke emerged from vehicle as I was driving. Then, the vehicle started overheating. Mechanic indicates head gaskets were blown and short block screws stripped and bent, leaking coolant on my 4 cylinder 2003 Highlander. He repaired the same make, model and year the prior year with the same issue. $69,000 for a new engine. $44,00 for a rebuilt one. I have never had any mechanical issues with this car since I purchased it two years old in 2005. Although, I have kept up with the servicing, this type of sudden malfunction is a shocker.
Head bolts stripped in engine , 66K miles - coolant loss - all mechanics prefer to swap engine - Toyota service shop by me quoted me 5,000 for an engine and 1 year warranty. The car is worth 8,000 tops. Heartbroken by this - will have to find a way to make repairs on my own and hope to drive again.
I was backing my car from across the street. After shifting to drive, my car jumped back in reversed full speed crash in to my garage. I had my foot on the brake but wouldn't stop till it hit my garage wall.
While driving on the highway, my engine temp in my 4 cyl, 4wd 2003 Highlander suddenly spiked high. I had to pull of the road. Towed to dealer. Dealer said bolts on short block of engine were stripped and allowed coolant to leak out and engine overheated. I was at 68,000 miles, so over the warranty period. I took it to my local dealer and they said I had a bad water pump...I paid to have that fixed, but the car still overheated. I took it back to the dealer and they then said it was the engine itself..the short block, something about the screws were stripped, that I had gotten a bad engine with stripped screws. Dealers service manager told me this was a known issue on some 4cyl 2003 Highlander but couldn't help me as it was out of warranty!!! …
2003 4 cylinder Toyota Highlander. Coolant leak and subsequent need for a new replacement engine due to the defect of 3 rear engine short block screws/threads. Had less than 85K miles on vehicle, when found a coolant leak underneath engine block of vehicle in garage after having no issues prior with engine, radiator or any associated accessories to the coolant system/engine system of vehicle. Took to a Toyota dealer prior to any overheating or vehicle operation failures or radiator failure. Toyota dealer pulled engine manifold and cover off to investigate and found that when they pulled the three screws that connect the engine cover that cover the heads/cylinders, the threads associated with the screws came with them. The only fix per dealership determined to be a brand new short engine block and accessory replacement for $6,470. Date on this is August/2010. …
2003 Toyota Highlander with 110,000 miles started to overheat and lose coolant. Took it to dealership and learned that the cylinder head bolts had come loose due to the holes in the block being stripped. Toyota estimated $3000 to take the block out to a machinist to bore new holes, but if that didn't work it would cost $6000 to replace the block. I then took the car to a private mechanic who said it would cost $9600 to take out the block and send to machinist or buy a re-manufactured engine for $8200. The private mechanic stated this problem is due to faulty manufacturing of the engine and also stated that he sees this problem all the time in these types of vehicles. On the internet I have found consumers sharing the same stories about similar vehicles by Toyota with similar engines that have the same problem; some only lasting 70,000 miles. …
Engine complaints in other Highlander years
Frequently asked questions
How common are engine problems on the 2003 Toyota Highlander?
NHTSA has 87 complaints about the engine & cooling of the 2003 Toyota Highlander, 34% of the model year's 258 complaints. The component named most often is engine (14 mentions).
Is there a recall for 2003 Toyota Highlander engine problems?
No. NHTSA lists no engine & cooling recall for the 2003 Toyota Highlander, though it has 2 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2003 Toyota Highlander engine problems start?
Half of the complaints with a recorded mileage happened before about 108,000 miles, and 4% before 25,000 miles.
Is it dangerous?
Owners linked 1 crash, 0 fires and 0 injuries to engine & cooling problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.