Aisin U660E Transmission Rebuild & Repair in Glendale, AZ (Toyota Lexus)

Sun West Transmissions — Glendale, AZ. Free estimates, honest diagnosis and a 3-year / 40,000-mile warranty on qualifying rebuilds and replacements.

The Aisin U660E is a six-speed automatic transaxle used in many Toyota and Lexus front-wheel-drive and all-wheel-drive vehicles with V6 engines. It replaced the five-speed U151E in many applications during the late 2000s and became one of the most common Toyota transaxles of the following decade. Toyota built a strong reputation for reliability with it, but high mileage, heat and the belief that “lifetime” fluid never needs changing eventually catch up.

Sun West Transmissions in Glendale repairs and rebuilds the U660E for Toyota and Lexus owners across Phoenix and the West Valley. We see plenty of high-mileage Camrys, Highlanders and Siennas that their owners want to keep for years to come.

Vehicles with the Aisin U660E

• Toyota Camry and Avalon with the V6
• Toyota Highlander and Sienna with the V6, in many model years
• Toyota RAV4 with the V6
• Lexus ES 350 and Lexus RX 350 in certain years

Exact application years vary, and some models used closely related Aisin units. Four-cylinder versions of many of these vehicles used different transaxles. We confirm the exact model before quoting. For the earlier five-speed, see our U151E page.

About the U660E Design

The U660E uses a compact gear train with clutch-to-clutch shifting controlled by the engine and transmission computer through linear solenoids in the valve body. It is designed for smooth, quick shifts and fuel economy. Toyota’s fluid specification for this unit is a low-viscosity World Standard type fluid, and the transaxle has no traditional dipstick in most applications. Checking or filling it correctly requires the proper procedure at a specific temperature.

Common U660E Problems

Harsh or Delayed Shifts

Owners sometimes report a hard downshift when coming to a stop, a harsh 2-3 shift or a delay when shifting into drive. Worn solenoids, a sticking valve, low fluid or degraded fluid can all cause it. Our harsh shifting page lists other possible causes.

Shift Flare and Slipping

At high mileage, clutch packs wear and the transaxle may flare between gears or slip under load. Arizona heat speeds up fluid breakdown, which accelerates clutch wear.

Torque Converter Shudder

A shudder or vibration at light throttle on the highway may come from the converter clutch or lockup control. Fresh fluid sometimes helps if caught early, but converter replacement may be needed.

Solenoid Failure

The linear solenoids control clutch pressure. When one fails or sticks, shifts can become harsh or erratic and codes may set.

Leaks

Axle seals, pan gaskets and cooler lines can leak. Because many owners never check the fluid on a sealed transaxle, low fluid often goes unnoticed until shifting suffers.

How We Diagnose a U660E

We start with a scan for codes and a look at live data, then check fluid level and condition using the correct temperature procedure, test solenoid circuits and road test the vehicle. Some complaints improve with a fluid service and adaptive reset, while others need solenoid or valve body work. If clutches are burnt or metal is present, a rebuild is the honest answer. Learn about our diagnostic process.

Our U660E Rebuild

1. Remove the transaxle and disassemble it completely.
2. Clean and inspect the case, gear sets, differential and valve body.
3. Install new clutches, steels, seals, gaskets and filter.
4. Replace worn bushings, bearings and solenoids as needed.
5. Service or replace the torque converter and flush the cooler.
6. Reinstall, fill with the correct fluid, reset adaptives and road test.

Qualifying rebuilds come with our 3-year / 40,000-mile warranty.

U660E Rebuild Cost

Cost depends on the vehicle, the damage found inside, the converter and whether solenoids or valve body work are needed. A remanufactured transmission may also be an option. We give free estimates after diagnosis. For model details, see our Toyota Camry transmission repair page and our Toyota transmission problems overview. Financing is available.

Is “Lifetime Fluid” Really Lifetime?

Many Toyota owners are told the fluid never needs changing. In Arizona’s heat, with stop-and-go traffic, the fluid works much harder than in milder climates. A periodic fluid service, using the correct fluid and fill procedure, is inexpensive protection. Read our guide on how often to change transmission fluid.

Aisin U660E Transmission FAQ

Does the U660E have a dipstick?

Most applications do not. The fluid level is checked at a plug with the transmission at a specific temperature, so it is best done by a shop.

Can I use universal transmission fluid?

We recommend the fluid type Toyota specifies. The wrong fluid can change shift feel and may lead to problems.

Is a high-mileage U660E worth rebuilding?

Often, yes. These vehicles tend to have durable engines and bodies, so a rebuilt transaxle can extend their life significantly.