2004-2010 Toyota Sienna: problems, engine, what to look for

Toyota engineer Yuji Yokoya was tasked with redesigning the 2004 Sienna for the North American market. To understand what North American minivan owners need, Yokoya drove the vehicle all over Canada, the U.S. and Mexico. This experience has been vital in improving the Sienna. As a result, the 2004-2010 Sienna is larger, more maneuverable and offers more storage compartments, cargo space and many other improvements.

The Toyota Sienna comes with front- or all-wheel drive in a 7- or 8-passenger configuration. Overall, it's a good minivan with solid powertrain, but there have been some problems to watch out for.

Reported problems: Several owners mentioned problems with the sliding doors. According to the Toyota bulletin POL12-02, the warranty for the Rear Sliding Door Latch Assemblies and Power Sliding Door Cable Assembly has been extended for some models to 9 years or 120,000 miles for certain Toyota Sienna models.
We found several Youtube videos on power sliding door cable repair. The repair is not easy but doable. If you are buying a used Toyota Sienna, the model with manual sliding doors is a preferred choice, as more power options means more expensive repairs. Here are a few videos on sliding door lock actuator motor repair/replacement.
In general, keeping the sliding door rails clean and lubricating the moving parts that need to be lubricated will help to avoid expensive repairs. The front door checker's mounting panel spot welds can become detached. Toyota has issued a warranty extension. If out of warranty, the repair is quite expensive. Watch YouTube videos on the subject. The symptom of this problem is a loud popping noise when opening the driver's or the front passenger's door. When buying a used Toyota Sienna, both front door checkers must be inspected carefully.

Many owners have reported cracks in the dashboard at higher mileage. This thread discusses the issue and possible fixes.

Exhaust leaks have also been mentioned. A local muffler shop is the best place to go for these types of repairs, as they can weld/repair damaged portion instead of replacing with expensive parts.

Leaking valve cover gaskets at higher mileage are not uncommon. Read more: When does the valve cover gasket need to be replaced?

Oil cooler lines in the 2007-2010 models are another common source of leaks. Toyota has issued the Warranty Enhancement Program ZE2 to address the problem. Read more in this forum.

There are many reports that a failed ignition coil can cause the engine to run rough and the Check Engine light to come on. Further diagnostics may show trouble codes P0351-P0356. Ignition coils for the cylinders 2, 4 and 6 are located in the front of the engine and are easy to replace. The ignition coils 1, 3 and 5 are located at the rear cylinder bank under the intake manifold that will have to be removed to get access to rear coils. If one of the ignition coils need to be replaced, it might be a good idea to change all the spark plugs as well if they are old. The repair shop may charge 2.6-3 hours labor plus the parts to replace all 6 spark plugs. It's recommended to use Toyota original parts for repairs.

Several owners mentioned replacing a leaking steering rack. With an aftermarket part, the repair may cost $400-$650. The intermediate steering shaft can fail too. The part is about $180-$370, plus $90-$220 to replace. A bad steering rack or intermediate shaft can cause a rattling noise in the steering when driving on a rough road.

Engine: The only powertrain choice is a transversely-mounted V6 with a 5-speed automatic transmission. The 2004-2006 Sienna has a 230-hp 3.3L V6 (3MZ-FE). For 2007, the Sienna received a 266-hp 3.5L V6 (2GR-FE). The 2007 FWD Sienna is rated at 17/24 mpg city highway. This means that on a long highway trip, you can get up to 440 miles (708 km) on a 20-gallon (75.7 liters) tank of gas.
The 3.3L V6 engine (3MZ) in the 2004-2006 Sienna has a timing belt that must be replaced every 90,000 miles. Replacing a timing belt with a water pump may cost from $690 to $940. The 3.5L V6 (2GR) in the 2007-2010 Sienna has a maintenance-free timing chain. Read more: When does the timing chain need to be replaced?

What to look for when buying a used Toyota Sienna: If it's the 2004-2006 Sienna, check the service or vehicle history records (if available) to see if the timing belt has been replaced. It's also good to know if the vehicle has been maintained regularly in the past. Check the NHTSA website for recalls that have not yet been completed.

When checking at the dealer's lot, check the area of the front door strikers for broken welding spots. Watch out for leaks under the hood. A low coolant or engine oil level or the smell of oil/coolant under the hood should warrant further investigation for possible leaks.

Watch out for uneven tire wear. Test all electrical accessories, try if the sliding doors are opening and closing properly. Test the heater and the A/C. Watch out for warning lights staying on on the dash after the engine is started. The blue smoke from the exhaust is a sign of engine problems.

When test driving, the transmission should shift smoothly without delays or slipping. See if the vehicle holds the straight line well. A rattling noise felt in the steering when driving slowly on a rough road, indicates possible problems with steering parts, such as the steering rack or the intermediate shaft U-joints.