Common Lexus RX300 Transmission Problems with Easy Solutions 2024

Lexus RX300 Transmission

Lexus RX300 transmission problems are not avoidable. If you own and drive the Lexus RX300, you will encounter some transmission issues at some point in time. This is why you need to get yourself familiar with these major problems and know what to do to correct or resolve them when they arise.

Usually, when you encounter or have to deal with any transmission issue with your RX300, the best approach is to consult an expert or transmission technician. A technician or specialist has the experience and skills to address your concerns for the best outcomes.

However, it would be best to consult the ideal or appropriate technician to fix the issues quickly and skillfully if you got yourself familiar with these problems.

Lexus RX300 Transmission Review

2001 RX300 Transmission

The transmission is an important component of your vehicle’s mechanical system. This component controls the amount of power released from the engine to the driveshaft so that you can drive your vehicle at the desired speed. Unfortunately, just like every mechanical unit or component, the transmission wears out after some time (as your vehicle ages and covers more miles).

The constant heat and friction causes wear and tear due to your vehicle’s moving components. Without proper maintenance, the transmission goes bad or gets faulty faster than usual. The transmission system repair can be difficult, costly, and stressful. This is why it is crucial to adhere to adequate maintenance routines to keep it healthy and in top working condition.

When the transmission is adequately maintained, and issues are detected and fixed accordingly, your vehicle is guaranteed to remain solid for an extended period. In addition, you won’t have to conduct transmission-related repairs from time to time.

A minor issue with the transmission affects your vehicle’s overall performance if not corrected or fixed on time. Whenever you detect or perceive any strange activities in your Lexus RX300, ensure you consult a mechanic to diagnose the issue and fix it immediately.

Transmission issues are not hard to detect. A faulty transmission’s common signs or symptoms include grinding and shaking when your vehicle is at speed, delayed shifting, fluid leaks, and burning smell. Also, you may experience whining or humming sounds emanating from beneath the hood.

Features & Specifications of First-Generation Lexus RX300 U140E / U140F

The first Gen of RX 300 are models produced from 1998 to 2003. These models are designed with a 3.0L V6 engine (220hp and a solid 222 lb-ft torque).

This generation of RX300 uses gasoline, with an option of either FWD (Front-wheel-drive) or AWD (All-wheel drive), and the engine is paired to a 4-speed automatic transmission (4AT).

In 2000, there was a mini-upgrade or refresh to the 1st Gen of RX 300. Headlights and interior options were incorporated, and the colors were also updated.

Features & Specifications of Second-Generation Lexus RX300 MCU30 / MCU35

Lexus RX300

The second Gen of RX 300 was launched in 2003, representing the 2004 model. This was when SUVs started making headlines, thereby gaining more attention among automobile enthusiasts around the world.

RX 300 designed from 2003 to 2008 are categorized as the second generation. Some impressive features of the 2003 model include the sleek appearance/design, air suspension system, adaptive cruise control, front headlights, tech-inclined wiper (rain-sensing), and 3.3L V6 engine (230hp and a solid 238 lb-ft of torque).

The 2005 Lexus RX300 (debuted in 2006) operates on a 3.3L V6 engine with 268hp, and the 2007 and 2008 Lexus RX300 runs on a 3.5L V6 engine with 270hp. The modification made to the 2008 model includes the door handles, improved front grille, wheel designs, paint options, and door handles.

The 2nd Gen operates on a 5-speed automatic transmission (5AT) against 4-speed automatic transmission in the 1st generation. As a result, the second-generation Lexus RX300 offers improved performance with an impressive fuel consumption rate.

Common Lexus RX300 problems

  • Tailgate rattle
  • Engine sludge build-up
  • Bonnet problem
  • Starting problems or irregular idling
  • Faulty transmission
  • Boot motor failure
  • Engine problems

Common Lexus RX300 Transmission Problems & Solutions

01. Lack of Response Problem

This is one of the most common transmission issues you may experience with your vehicle. For instance, if you drive an automatic transmission vehicle like the Lexus RX300, the vehicle is expected to shift from one gear to another smoothly and without delay. If you start witnessing delays or find it hard to switch the gear into drive or park, you need to detect the problem and fix it immediately.

Suppose you conduct a clutch or transmission repair or replacement recently. If not done correctly, it could contribute or result in delayed shifting or lack of response.


Consult an experienced mechanic to conduct an intensive check, and fix the issue accordingly.

02. Leaking Fluid Problem

Lexus RX 400h 2008 Water Leak found

If you detect or notice a fluid (reddish) leaking from your vehicle, your transmission needs to be checked immediately. The transmission fluid is an essential component of the transmission. Its functions include lubricating, cleaning, and conditioning any seals, and at the same time, acts as hydraulic fluid.

When the transmission fluid leaks, this results in a drop or decrease in the fluid level. Suppose you ignore this sign and continue driving your vehicle while the fluid is at its lowest level. In that case, the engine’s performance could be affected. It may also lead to severe or expensive damage to the transmission, which can only be fixed with a replacement or rebuild.


Immediately detect any fluid dripping or dropping from your vehicle, immediately take your vehicle to the mechanic workshop. This allows an experienced technician to detect the issue and fix it accordingly.

03. Burning Smell or Odor Problem

Transmission fluid could either have a moderately sweet or tart smell whenever you perceive or detect this smell, combined with a slight burning odor. This could indicate an overheating transmission fluid.

When the transmission fluid is excessively heated (darker fluid), it could result in extreme or severe friction issues among the moving components in the transmission.


Once you perceive a burnt smell resulting from the overheated fluid, turn off the ignition, and allow the engine to rest for a few minutes. Afterward, replace the fluid. In some cases, some repairs may need to be done. This is why it is advised to consult an expert to detect the problem and fix it professionally.

04. Grinding Noises Problem

This is another common sign of a damaged, faulty, or troubled transmission. This sound is perceived or detected during shifting. In most cases grinding noises are associated with insufficient or low transmission fluid in the transmission.


Suppose you hear or perceive any strange noise coming from your vehicle. Do not hesitate to consult an experienced mechanic to detect the fault and get it fixed.

05. Transmission Warning Light Problem

The Lexus RX300 comes with a transmission indicator light. Whenever the transmission warning light comes on (noticeable on the dashboard), this could result from overheating. In some cases, the transmission indicator light could come on due to an electrical issue or malfunction.


When the transmission warning light turns on, make sure you get the problem diagnosed and fixed as soon as possible. Failure to act accordingly (leaving the issue unattended for a long time) could result in severe issues that may be difficult and costly to fix.

06. Valve Body Issues Problem

This issue is peculiar with the 1999 RX300 models. What happens is that your vehicle shakes during the 2 to 3 shift while operating or driving under light throttle. This issue typically occurs when the transmission attained operating temp. The problem is associated with a flaw in the valve body design and was eventually fixed in newer models.


A seasoned technician or mechanic can correct this issue by replacing the affected valve body with a revised design.

Lexus RX300 Transmission Replacement Cost & Service Cost

Lexus RX300 transmission replacement (a new system) costs between $2000 and $3500 (a rebuilt transmission costs slightly below these prices). A used or second-hand transmission costs between $1000 and $1500, excluding the labor cost.

On average, it cost about $200 to flush, change, or replace your vehicle’s transmission fluid. Depending on the transmission, you will need between 8 and 12 quarts of fluid—a quart of transmission fluid costs between $8 and $20.

The cost of a new filter ranges between $15 and $30, and pan gaskets cost between $75 and $150. In addition, the labor cost for minor issues or repairs may cost about $150.

Reliability of Lexus RX300

Lexus RX300 is owned and manufactured by Toyota. All around the world, and in the history of automobiles, the brand Toyota has a great name and strong presence. Also, the brand equity is solid. Thanks to its excellent vehicle designs, it is known for stable and long-lasting performance and a reliable & comfortable driving experience. Also, when you adopt or follow a proper maintenance routine, the second-hand or resell value is excellent.

Lexus RX300 models are built or designed to last up to 180 thousand miles on average. With proper maintenance (when you follow the manufacturer’s procedures and guidelines), about 300 thousand miles is achievable.


Common Lexus RX300 Transmission Problems with Easy Solutions faq

What is 5-speed automatic transmission, and how is it different from a 4-speed automatic transmission?

A vehicle that is paired to a 5-speed automatic transmission (5AT) uses 5 drive gears. While a 5AT vehicle operates on 5 different drive gears, a 4AT vehicle operates on 4 drive gears. Also, the 5-speed automatic transmission offers a more incredible combination of fuel efficiency and power.

One feature 4AT and 5AT have in common is that both transmissions are automatic. The vehicle that runs on either transmission decides when gears need to be switched and does the job for you. Basically, your own role is to drive.

How often do I have to get the transmission replaced?

Usually, how long the transmission lasts depends mainly on the level of maintenance on the part of the vehicle owner, driving style, and factory design (in case there are flaws). But, on average, Lexus RX300 transmission can last up to 180 thousand miles.

When your vehicle is properly and adequately maintained and taken care of, and with the factory design flaws appropriately addressed, your transmission can last longer.

What happens when Lexus RX300 transmission issues are ignored?

When transmission issues are not corrected or fixed immediately, they occur. This could result in a noticeable reduction in fuel economy or efficiency. In some cases, you may not be able to drive your vehicle at all.

If you notice or detect any faulty transmission signs, do not ignore them. However, when you decide to keep driving your vehicle (in a situation where the problem is not critical or a slight adjustment is needed), this action could lead to excessive or severe damage to other expensive parts or components in your vehicle transmission.

How can I diagnose Lexus RX300 transmission issues?

It is somewhat easy to guess the actual problem or issue with your transmission. Nevertheless, you need the right tools and knowledge to identify the problem accurately. When you take your vehicle to an expert (an experienced mechanic or a reliable diagnostic center), a computer will be connected to your Lexus RX300 to find out and read the trouble codes. Upon identifying what exactly to check for, a visual inspection is then performed to verify the issue.

How is Lexus RX300 transmission repair or replacement performed?

Before you can conduct a transmission replacement, you have to lift your vehicle off the ground to allow easy access to various components that you must unscrew before the transmission can be accessed and eventually removed from its compartment.  Next, the transmission is pulled down using a transmission jack, and then a new unit is then installed accordingly.

What Is The Average Cost Of Fixing RX300 Transmission?

The cost of fixing an RX300 transmission can vary depending on several factors. Generally, the cost of transmission repair or replacement can range from $1,800 to $3,400 or even higher, depending on the extent of the damage and the type of repair required.

Minor transmission repairs such as replacing a faulty sensor or solenoid can cost between $150 and $400. However, if the transmission requires major repair work, such as a complete overhaul or replacement, the cost can be significantly higher.

Other factors that can affect the cost of fixing an RX300 transmission include the labor rates of the mechanic or repair shop, the cost of replacement parts, and the location where the repair is being done.

How Do I Maintain My AWD Or FWD Auto-Trans System?

To maintain your AWD or FWD auto-trans system of your RX300, you can follow these steps:

  1. Regular fluid changes: The transmission fluid plays a vital role in keeping the transmission system working correctly. Therefore, you must change the transmission fluid at regular intervals as per the manufacturer’s recommendation. This will help prevent wear and tear of the transmission system and extend its lifespan.
  2. Check the transmission fluid level: It is also essential to monitor the transmission fluid level regularly. Low fluid levels can cause the transmission system to overheat and damage it. Therefore, make sure to check the fluid level periodically and top it up if necessary.
  3. Inspect the transmission system for leaks: Leaks in the transmission system can cause damage to the transmission system, and it can be expensive to repair. Regularly inspect your RX300 for any signs of fluid leaks and get them fixed as soon as possible.
  4. Drive smoothly: Aggressive driving can put unnecessary stress on the transmission system, leading to damage. Therefore, it is crucial to drive smoothly and avoid sudden acceleration or deceleration.
  5. Service the transmission system regularly: Getting your RX300’s transmission system serviced by a professional at regular intervals is crucial to keep it working correctly. During the service, the technician can inspect the system for any issues and fix them before they become significant problems.

By following these steps, you can maintain your AWD or FWD auto-trans system of your RX300 and keep it working correctly for a long time.


Lexus RX300 transmission problems are easy to detect, provided you understand the signs to watch out for. If you decide to service your transmission (flush out or clean the system), ensure this is done rightly. You can either take it to a seasoned technician or follow the manufacturer’s recommendation if you are doing the cleaning on your own.

When you keep the transmission clean, it operates smoothly. This prevents expensive repairs, changes, or adjustments in the future.

You can clean or flush the transmission system after completing 60,000 miles, and do not forget to replace the filter. Consecutive cleaning and flushing can be done after every 30,000 miles covered. When you adhere to this basic maintenance routine, your transmission stays healthy, lasts longer, and your vehicle’s overall performance, and condition is greatly improved.

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