In general, the Toyota Sienna is quite a good minivan. One of its main selling points is that Toyota is considered a reliable brand and the Sienna holds up this reputation pretty well. However, like many manufacturers, Toyota did struggle with some transmissions for the past decade. Here´s a quick summary:
Toyota Sienna, made from 2021 onwards, has a problem-free eCVT transmission. 2011 – 2020 Sienna, had problems with the 8-speed UA80E automatic, causing harsh shifting, reduced power, and check engine lights due to a wrongly installed washer tab. Furthermore, 2005 – 2010 Sienna with a 5-speed U151E transmission had problems with the shift lock assembly causing a rollaway risk.
However, that certainly doesn´t tell the whole story. Below, we´ve outlined all transmissions used in the Sienna since 2004. Furthermore, we go through each of them and explain the technical service bulletins, recalls, and complaints we´ve found about them. Read on!
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Common Toyota Sienna Transmission Problems
Now, let us see some common problems with transmissions used in the second, third, and fourth generations of the Toyota Sienna. If you want to know more about the general problems that you should look out for when buying a Sienna, click the article we just linked.
Fourth Generation (2021 – Present)
The fourth generation of the Toyota Sienna only uses an eCVT transmission, and this unit seems to be reliable.
When we went through the NHTSA complaints and recalls for the fourth-generation Sienna (the only generation that uses this eCVT), we didn´t find any complaints regarding the transmission. Technical service bulletins have also not been issued; therefore, we don´t have any reason to believe this would be an unreliable transmission.
Third Generation (2011 – 2020)
The third generation of the Sienna used the following transmissions:
- 6-speed U660E automatic (2011 – 2016)
- 8-speed UA80F automatic (2017 – 2020)
The 6-speed transmission was quite a good unit, whereas the 8-speed unit did cause some problems when it was first introduced.
6-Speed Automatic (U660E)
The U660E was used in the Sienna between 2011 – 2016, whereas the UA80F was used in the 2017 – 2020 Sienna, according to Wikipedia. Overall, both these transmissions were reliable and aren´t much complained about. The issues we mention below are rare, and it´s essential to consider this.
The U660E transmission didn´t receive any recalls or technical service bulletins in the 2011 – 2016 model years. Rare issues or points with the U660E that are worth mentioning are:
- The common issue with the transmission is the worn valve body. Contaminated automatic transmission fluid and vitiated torque converter lockup cause slagging or wear-out of plunger valves and channels of the valve body.
- In the electrical part, the selector position plate with temperature is the most commonly replaced element. The overheating sensor is the reason for the malfunctioning of the valve body.
8-Speed Automatic (UA80F)
The UA80F was introduced in the 2017 Sienna and was used up until 2020. However, it´s important to note that this transmission was complained about when it was first introduced in the 2017 – 2018 Sienna.
Sometimes, complete transmission failure is what the owners had to deal with (although really rarely in the Sienna). This either meant the transmission would fail while driving down the highway or the transmission wouldn´t go into gear anymore after a full stop and the car was in neutral. Other symptoms included harsh shifting, reduced power, and check engine light illumination:
There is a possibility that a washer tab, designed to prevent the loosening of a nut inside the affected transmissions, was not sufficiently bent during assembly. This could lead to the nut loosening and, over time, lead to the symptoms described above.Source, 2017 TSB
After this TSB, complaints for this transmission did drop for the Toyota Sienna. Other vehicles, like the Toyota Highlander and Camry, kept on having problems, but this is not the case for the Sienna.
Second Generation (2004 – 2010)
The second generation of the Toyota Sienna made use of two transmissions from the same family:
- 5-speed U151E automatic (FWD)
- 5-speed U151F automatic (AWD)
5-Speed Automatic (U151E/U151F)
Overall, this 5-speed automatic hasn´t caused many problems at all. However, there was a widespread recall for the 2005 – 2007 and 2009 – 2010 Sienna due to a problem within the shift lock assembly. The shift lever may have been moved out of the ‘Park’ position without depressing the brake pedal. This caused Sienna to roll away.
Sometimes, these transmissions caused flaring, slipping 2-3 shifts, or binding on the 3-4 shift. These problems are typically resolved by performing a transmission memory reset. If this is not the solution, there´re ways to check if the solenoids are causing the problems.
Also read: The Types Of Gas A Toyota Sienna Uses (Explained)
How Long Does A Toyota Sienna Transmission Last?
Generally, we expect a Toyota Sienna to last between 240,000 – 270,000 miles. After doing the above-stated research, we have concluded that we have no reason to believe that Sienna transmissions will fail before this mileage is reached.
The only model years we would be a bit more hesitant with are the 2004 – 2005 and 2017 – 2018 model years. Because these model years are the first two model years in their generation, and they introduced new transmissions, there were some hiccups. However, transmission failure is rare in all transmissions that are used in the Sienna, which is a very strong sign for the Sienna.
How Much Does A Toyota Sienna Transmission Cost?
It is a good idea to know the prices of different transmissions when you look for a replacement. For this purpose, we mention the costs of some of the transmissions to help you make up your mind.
- 5-speed U151E/F automatic: $2,708.00 (Reman-transmission)
- 6-speed U660E automatic: $1,299.00 (Jdmnewyork)
- 8-speed UA80E automatic: $4,600.00 (parts.lexus.com)
Hi! My name is Stefan; I’m the owner and lead writer at TheDriverAdviser.com.
I’m an active writer on this blog myself, as well as a novice car mechanic. For the really technical stuff, I find writers with experience as a mechanic or who have studied mechanical engineering.
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