Toyota Motor Corporation manufactures reliable vehicles, but in some cases, even Toyota and Lexus owners may experience transmission problems.

In this guide, we go over common transmission problems that affect Toyota and Lexus vehicles, symptoms and how to read fault codes from the Transmission Control Module. 

Symptoms

transmission problems

 

Symptoms of Toyota transmission problems:

  • Vehicle stuck in gear
  • Rough or delayed shifting
  • Transmission won't shift gears
  • Loss of power, no acceleration
  • Delayed or harsh shifting
  • Hesitation
  • Jerking when changing gears
  • Check engine may come on
  • Vehicle gets stuck in gear, limp mode

Common Problems

Toyota and Lexus transmission problems can range from internal transmission wear which is common on high mileage vehicles to the valve body and electronics failure. 

Let's take a look at common Toyota transmission problems. These problems may also affect Lexus vehicles. 

Low Transmission Fluid Level

check transmission fluid level

One of the most common issues that cause Toyota transmission to not shift, delay shifting or bang in gear is low transmission fluid.  As the car ages transmission fluid leaks become more common.

Possible Solution

Check the transmission fluid level as soon as possible. 

  1. If the vehicle is drivable drive it for 15 min to warm up the transmission fluid. 
  2. Leave the car running and place the transmission in Park. 
  3. Pull the hood release under the dashboard and open the hood. 
  4. Locate the transmission dipstick. Toyota check transmission fluid level
  5. Press the metal retainer to the side and pull out the dipstick. 
  6. Clean the dipstick with a clean cloth and reinsert it fully in the same tube. 
  7. Pull the dipstick again and note the transmission fluid level. There are two ranges. One if the transmission fluid level is warm and one if the transmission fluid is cold. Check toyota transmission fluid level
  8. If the level is low add ONLY the recommended transmission fluid to bring the level between the MIN and MAX marks. Do not overfill past the MAX mark on the dipstick. 

Please refer to the owner's manual for the exact procedure for your model. 

A transmission should not lose fluid, burn it or leak it. If your transmission fluid level is low there is a chance you have a bad gasket on the transmission fluid pan. 

Shift flare when going from 3rd to 4th gear

Toyota transmission problems

Many Toyota and Lexus cars suffer from occasional shift flare, which shows up as a brief pause when shifting from 3rd to 4th gear. During this pause, the engine speed will increase, as the transmission is slipping. This only happens once or twice after the vehicle is started from cold.

Possible causes

  • Transmission control module (TCM) software is not appropriate for the climate. Reflashing the TCM using suitable software can solve the problem. See an appropriate Technical Service Bulletin (TSB)
  • A weak battery or corroded battery terminals, which can cause a transmission control module (TCM) to reset and go into re-learning mode. Check battery voltage and clean off any traces of corrosion on terminals.
  • Low or degraded transmission oil or sticking solenoids. Replace oil with filter and clean the solenoids if needed.

Incorrect shifting or staying in the same gear for too long

Toyota transmission issue

At higher mileage, many Toyota and Lexus cars can experience incorrect shifting. This will show up as delayed and unusual gear changes or lack of downshifts when trying to accelerate.

The problem can be constant or intermittent, and sometimes it may trigger a check engine light.

Possible causes 

  • Throttle position sensor that is faulty or out of adjustment. In most cases, this will trigger a check engine light and corresponding fault. The operation of the throttle position sensor can be monitored and verified using most diagnostic tools.
  • Shift solenoids that are faulty or clogged. If the fault is electrical, it may trigger a check engine light. Mechanical issues and clogged solenoids will rarely result in a check engine light.
  • Check the transmission fluid level and top it off if needed. If you don’t know when it was changed last time, consider replacing it together with a filter.

Grinding or rattling noise while driving

Toyota transmission stuck in gear Park

When the car is in the drive, it produces a grinding noise. This may happen when it is started from cold and go away as it warms up, or it can be present all the time.

The frequency of the noise follows the engine speed.

Possible causes

  • A torque converter has several needle bearings inside, which can wear out or get damaged as a result of poor maintenance. In addition to noise, this can create noticeable vibrations during accelerations
  • Check the transmission fluid level and top it off if needed. If you don’t know when it was changed last time, consider replacing it together with a filter.

Burnt transmission fluid

Sometimes, especially during long drives or under heavy loads, you may notice a strong smell of burnt oil inside the car.

If this is accompanied by transmission issues, such as hesitation or gear slipping, your transmission may be overheating. This shouldn't be ignored, as it can cause irreversible damage.

Possible causes

  • All automatic transmissions have coolers, which keep the transmission temperature within limits. In most cases, this cooler is integrated into the engine radiator. If it is clogged or if connecting lines and pipes are broken, there will be no sufficient cooling.
  • Make sure that the fluid type that is in your transmission matches manufacturers' specifications. Most cars use ATF, but there are some who use Pentosin.
  • Check the transmission fluid level and top it off if needed. If you don’t know when it was changed last time, consider replacing it together with a filter.

Hesitation and harsh shifting from 1rd to 2th gear and vice-versa

 

This is a problem that affects newer Toyota and Lexus cars that have an 8-speed automatic gearbox.

When attempting to accelerate after slowing down to an almost complete stop, transmission often has trouble deciding on which gear to select.

This causes lag in response time and results in harsh gearshifts.

Possible causes 

  • Contact your dealer and check if there is an outstanding Technical Service Bulletin (TSB) for your vehicle. Reflashing the TCM using suitable software can solve the problem.
  • Try adapting your driving style so you apply less throttle in situations described above, as this will stop it from going into 1st gear.

CVT transmission in limp-mode

This is a known problem for all 2014-2017 Toyota Corolla and Scion cars. In certain situations, CVT transmission can go into the ‘limp-home’ mode.

The check engine light will be illuminated on the dashboard, and there will be a reduction of maximum vehicle speed at approximately 37 mph.

Possible causes 

  • An error within the transmission software can cause solenoid valves to experience unnecessarily cycling, which can lead to excessive wear. This can be prevented by reflashing the TCM using suitable software. Check on https://www.youcanic.com/recall if your vehicle is subject to ‘Special Service Campaign J0D’
  • If your car is going into limp-mode, solenoid valves are irreversibly damaged and must be replaced. In some situations, the damage may extend to the whole CVT transmission.
  • In initial stages, the only symptom may be a check engine light accompanied by a P2820 code stored in the vehicle fault memory.

It is important to find out which transmission is installed in your Toyota or Lexus and research the problems that affect that particular transmission. To find out which transmission model is installed on a Toyota call the dealer or run a VIN Decoder. 

Diagnose Toyota Lexus Transmission

diagnose Toyota Lexus transmission problems

Even though Toyota / Lexus transmissions are complex the good news is that most problems get detected by the Transmission Control Module (TCM) and a fault code will be stored in that module.

Transmission problems won't always trigger the check engine light. A generic scanner in most cases won't show a fault code at all. Instead of using a generic OBD-II scanner, use a scanner that can read Toyota transmission fault codes.

What you will need

Procedure

  1. Park vehicle, set the parking brakes. 
  2. Locate the diagnostic port under the dashboard and plug in your scanner. Toyota obd2 port
  3. Turn on the ignition and the scanner. 
  4. Select Toyota forms the main menu and then your model. 
  5. Select the Transmission Control Unit. 
  6. Scroll down to Read Fault Codes. 
  7. Write down all the codes and their definitions. Pay close attention to codes that have current or present status. 
  8. Research each code further to find out what may have caused each fault code. 

Spend a few minutes to become familiar with Toyota and Lexus transmission problems.

Even if you don't plan on fixing the problem yourself having an idea of what can be wrong can make you more confident when you communicate with your mechanic.