Lexus GS300 Transmission Problems - Common Issues and Fixing Tips

The Lexus GS300 is a very dependable car. It has a sporty look with a performance that backs it up. The interior of the vehicle is also widely praised for its comfort features, which are complemented by its exemplary driving dynamics. However, all these could be easily ruined by a bad transmission.

A340E transmission highlights

• Average lifespan:260,000-290,000 miles
• Reliability Score:High
• Prone to minor issues:No
• Price for repair after failure:$700-$1,000
• Price for replacement:$2,000-$3,200
• Availability of parts:Bad
• Common problems: Friction plates wear faster in heavy cars, fluid leaks are possible, gears are afraid of low fluid level.

A350E transmission highlights

• Average lifespan:240,000-260,000 miles
• Reliability Score:High
• Prone to minor issues:No
• Price for repair after failure:$900-$1,200
• Price for replacement:$3,000-$4,200
• Availability of parts:Bad
• Common problems: Friction plates wear fast, fluid leaks are possible, fluid pump may suffer.

Most Common Complaints About the Lexus GS300 Transmission

Based on customer reviews and reports, these are the common complaints related to the transmission system of the Lexus GS300:

1. Shifting Delay

Shifting delay or lag is a common issue with automatic transmissions and with aged Lexus GS300 units. When the transmission shifts gears, there can be a slight delay before the engine speed catches up. This lag can cause the car to jerk or hesitate when accelerating.

2. Loud Revs

When there is a lag in shifting in your automatic transmission, it can cause the engine to loudly rev up and then suddenly drop down in RPMs. This can cause the car to jerk or lurch forward, and it can be extremely uncomfortable for passengers. In some cases, it can even damage the transmission.

3. Suddenly Shifting in Neutral

This is another form of slippage where your car will suddenly shift to Neutral and it refuses to engage Drive anymore.

4. Strong Vibrations and Noises

The slippage can be accompanied by strong vibrations and noises coming from underneath your car. The noises can be in the form of whirring or knocking sounds while running your car or even when idling.

5. Burning Smell

A burning smell can manifest together with any or a combination of the aforementioned problems.

Common Causes of the Issues in the Lexus GS300 Transmission

There are a few reasons for the common transmission problems of the Lexus GS300. One possibility is that the transmission fluid is low or dirty. This can cause the gears to slip, not engage properly, make noise, vibrate, or overheat. Another culprit is that the sensors or the transmission are worn out and need to be replaced.

1. Low Transmission Fluid

Most of the common Lexus GS300 transmission failures is due to insufficient transmission fluid. If your car is low on transmission fluid, it could potentially cause a wide variety of problems.

The transmission fluid is responsible for lubricating and cooling the various components within the transmission, so if it's low, those components can start to overheat or seize up. This can lead to a host of issues, including decreased performance, slipping gears, and eventually complete failure of the transmission.

To avoid these potential problems, it's important to keep an eye on your transmission fluid level and top it up when necessary. Here's a quick guide on how to do that:

• Park your GS300 on a level surface and engage the parking brake.
• Locate the dipstick. It should be on the driver's side of the engine, near the front.
• Pull out the dipstick and wipe it clean with a rag.
• Reinsert the dipstick and then pull it out again to check the fluid level. The fluid should be between the "Full" and "Add" markings on the dipstick.
• If the fluid is below the recommended mark, add more until it reaches the "Full" mark. The tube of the transmission fluid reservoir is so narrow, so you should use a long funnel when pouring a new batch to avoid spilling the contents into the other parts of the engine bay.
• You can use any type of transmission fluid for this. Just make sure it's compatible with your GS300.
• Replace the dipstick and close the hood of your car.

By keeping an eye on your transmission fluid level and topping it up when necessary, you can ensure the performance of your transmission for years to come and mitigate your risk of encountering any problems connected to it.

2. Dirty Transmission Fluid

It's highly recommended that you change your transmission fluid every 30,000 miles or more often if you frequently use your vehicle on city drives. Unfortunately, changing your transmission fluid is not a simple process and you can't probably do yourself.

You'll need a catch pan, a socket wrench, a ratchet, a funnel, and the transmission fluid recommended by your car manufacturer before anything else. Also, you will need some equipment that will help you get the most of the old fluid out of the tranny. Then, proceed with the following steps:

• Lift your car. You'll need to get under the car to access the transmission fluid drain plug, so it's important to make sure the car is securely lifted off the ground. Use a jack to lift the front or back of the car, depending on where the drain plug is located.
• Locate the transmission fluid drain plug. If you're unsure where to look, consult your vehicle's manual. In most cases, it will be near the bottom of the transmission pan.
• Remove the drain plug. Use a socket wrench to loosen the drain plug, then remove it completely by hand. Be careful not to misplace the washer that comes with the drain plug.
• Allow the fluid to drain. Place a catch pan under the transmission pan to collect the fluid as it drains out. Depending on the size of your catch pan, you may need to empty it a few times during this process.
• Clean the drain plug and reinstall it. Once all the fluid has drained out, use a clean rag to wipe off the drain plug. Be sure to also clean the threads in the transmission pan. Then, reinstall the drain plug and tighten it with a socket wrench.
• Add new transmission fluid. Once the drain plug is back in place, you can begin adding new transmission fluid. First, use a funnel to pour the new fluid into the transmission dipstick tube. Then, check the dipstick to make sure the fluid level is at the "full" line. Add more if needed.
• Lower your car and test-drive it.

Once you've added the new transmission fluid, lower your car back down to the ground and take it for a spin. Observe how the car shifts gears, and if everything seems to be working properly, then you're all done!

Unfortunately, this will just replace about one third of the fluid presented in the transmission, so for a full change you should go to a repair shop or a dealer.

3. Transmission Sensor Failure

If your Lexus GS300 is experiencing transmission sensor failure, it is important to act immediately. A bad sensor is prone to sending the wrong signals to your powertrain control module (PCM), which can confuse the system and prevent the synchronicity of your vehicle's moving parts. This problem can make your car lose power and stall, making it difficult to drive. It is also one of the primary causes of your transmission stick not shifting away from Park or Neutral.

• Replacing the transmission sensor can be done with a few basic tools. To replace the transmission sensor, you will need a new transmission sensor compatible with the model of your car, a ratchet set, a socket wrench, and a Phillips head screwdriver
• Start by locating the old sensor on the side of the transmission.
• Use a socket wrench to remove the two bolts that hold it in place. Carefully pull out the old sensor and discard it.
• Next, take your new sensor and insert it into the hole. Secure it in place with the two bolts.
• Finally, use a Phillips head screwdriver to adjust the sensor until it is snug.
• Test the sensor by starting your car and shifting your vehicle into Drive.

If all goes well, your car should operate normally.

4. Faulty Transmission System

The worst cause of your transmission woes is the system in itself. These can manifest through slippage, unusual noises, overheating, and leaks.

The tools needed for this job include a socket wrench set, a torque wrench, an oil filter wrench, a container, and a car lift or any platform to raise your car to a considerable height. Assuming that the vehicle is already raised and supported, proceed with the following steps:

• Remove the splash shield front underneath your car.
• Disconnect the transmission cooler lines from the radiator.
• Drain the transmission fluid into a suitable container.
• Disconnect the shift cable from the transmission.
• Disconnect the speed sensor and wiring harness from the side of the transmission.
• Disconnect the electrical connectors for the solenoids on the side of the transmission.
• Using a jack, support the weight of the transmission.
• Remove the bolts securing the transmission to the engine.
• Carefully lower the transmission and remove it from the vehicle.
• To install the new or rebuilt transmission, reverse the above steps. Be sure to fill the transmission with the appropriate amount and type of fluid.

Of course, it's much more rational to go to a repair shop for this. The process of replacing the transmission is not as straightforward as it may sound here, we only describe it for your understanding. It may include a lot of other important steps that you won't be able to do yourself in your garage.

Conclusion

It's best to address the transmission problems of your Lexus GS300 as soon as the symptoms start occurring. If you're not comfortable performing any of the fixes shown here by yourself, it's best to take your vehicle to a qualified mechanic or Lexus transmission specialist. Attempting this repair without the proper knowledge and tools can result in serious injury or damage to your vehicle.