Lexus IS250 Transmission Problems - What Should You Expect?

Arguably, one ugly fact is true about all cars: they all have at least one defect. We mean a 'congenital' factory issue that unflatteringly characterizes the car's maintenance. This fact has been a many-decade-long issue we've gotten to grapple with. It's always been that one car's strength is another's weakness. 

Lexus IS250 automatic transmissions highlights

• Average lifespan:180,000-200,000 miles
• Reliability Score:High
• Prone to minor issues:Partially
• Price for repair after failure:$1,300-$1,700
• Price for replacement:$4,700-$5,500
• Availability of parts:Average
• Common problems:sudden failure, limp modes, electronic glitches, very sensitive to any overloading.

The Lexus IS250 transmission is a six-speed automatic transmission designed to be smooth, responsive, and durable. It has a computer-controlled system that controls the shifting of gears. The Lexus IS250 transmission, together with its engine, provides a high level of performance and efficiency.

However, a lot happens, at times, that leads to unsavory ends, and a transmission problem can be one of such. What's more, the situation may start suddenly and can be frightening if you're in the middle of a journey.

Well, let's dive in and see what's inside. 

Lexus IS250 Overview

From the stable of a renowned car manufacturer, Lexus IS250 (2006 - 2013) is a luxury car with lots of exceptional options. It comes with a 2.5-liter inline-four engine that produces 204 horsepower and 186 lb-ft of torque. Its transmission is either manual or automatic, though the majority is automatic - like most cars in the US.

How Does Lexus IS250 Transmission Work?

Regardless of the kind of transmission your Lexus IS250 comes with, there is always a gear lever. In addition, a gearbox is always present to facilitate gear switches. The first significant difference between a manual transmission IS250 and an automatic transmission one is the presence of a clutch pedal. 

This article focuses on the automatic transmission of the Lexus IS250.

Since this car is automatic, the clutch pedal is missing, but it does have a clutch pack in the transmission. This pack is a drum with lots of discs and a piston inside. The piston, using oil pressure, automatically pushes the discs together. This action locks the clutch pack component and facilitates gear shifts without damaging your car. 

The most common Lexus IS250 on the market in the US has a 6-speed automatic transmission. They are either rear-wheel drive or four-wheel drive. But when you look beyond the gear lever, underneath, you have a labyrinth of interconnected components that form the drivetrain. The core at the center of the drivetrain is your transmission system.

Because your Lexus IS250 is automatic, your input in gear shifting is minimal. Moving the stick shift from neutral to drive or reverse through a linear channel is all you need to do. From that point, your car takes over every other thing, automatically changing gears.

Like the steering and brakes, the transmission system gives you lots of liberty to control your car. Otherwise, how would you have been able to back your vehicle up or travel at different speeds?

What are the Most Common Lexus IS250 Transmission Problems?

Your Lexus IS250 automatic transmission relies on sensors and mechatronics. In other words, it depends on a combination of mechanical, electrical, and software technologies to function well.

The transmission is on top-notched automobile technology, so it's a close-to-perfect system. However, it has its downside. Here are the most common transmission problems you should be expecting.

• Gears Slip

Lexus IS250 nearly always presents this as the first sign of a transmission problem. Under normal circumstances, the automatic transmission changes gear smoothly with the barest noticeable sign. However, when your car starts experiencing gear slips, all of that changes as the car struggles to select gears. Gear selection and engagement will become a bit 'rough.' You may notice that the car's speed falls behind the PRM.  

• Gear Shift Delays

Your Lexus IS250 should be ready to move once you shift the gear lever from neutral to drive. Unfortunately, a transmission problem may interfere with this sequence and cause the car to lag. The vehicle revs for a few seconds before the drive gear engages successfully.

The same issue may occur when you shift the gear lever into reverse.

• Car 'shaking' or 'jerking.'

A transmission problem may manifest as a 'shaking' or 'jerking' movement. Many drivers reported this movement as a typical hesitant reaction from the car. The situation may rapidly deteriorate if you do not take remedial action in time. 

• Burning Odor

When your car produces a burning odor, it may be because it's developed a transmission problem. Your vehicle uses a transmission fluid that starts smelling when the transmission overheats. At times, it may be that the transmission fluid is burnt and needs changing, or the whole system needs flushing.  

• Grinding sounds

Your car may start making unnatural grinding sounds when it changes gear. The sound may or may not be accompanied by shaking and jerking. However, it's almost always accompanied by speed pick-up difficulty.

• Mechatronic failure

Being an automatic transmission car, your Lexus IS250 transmission relies on many mechatronic components. Once there is a problem with any of these components, an instant transmission problem develops. It may cause your car not to start promptly or cause it to drive slower than usual. In very critical mechatronic failure, your car may lapse into a failsafe mode.  

• Unresponsive Car

This is probably the worst you could expect from your car, and it can be understandably nightmarish. It indicates a total break in transmission. Your car engine is powered, but the rotating crankshaft cannot power the transmission.

In some cases, the transmission fails, unable to transmit the power from the engine to the driveshaft.

What are the Vital Components of the Lexus IS250 transmission system?

• Torque Converter

This component is what replaces the clutch in your Lexus IS250 transmission system. Shifting gears requires a disconnection between the engine and transmission to prevent the gears from any damage. A torque converter performs this essential duty. It binds or unbinds the engine from the transmission through transmission fluid.

• Transmission Solenoid

This component is an electro-hydraulic valve that regulates fluid movement within an automatic transmission and the torque converter to communicate with the engine. It controls the transmission fluid pressure that directs the lockup clutch activities and relies on power from the transmission computer to function.

• Oil Pump

Like any other pump, this oil pump motorizes fluids. In this case, it runs transmission fluid from the transmission oil pan through the valve body to every component that needs fluid within the transmission system.    

• Planetary Gear Sets

These gears are different from what you'll find in a manual transmission car in that they are in sets and different sizes. There are three sets of these gears in your Lexus IS250. Though they are a little complex to understand, what they do is fantastic.  

• Clutch Packs

Your Lexus IS250 is an automatic transmission car, so it does not have a manual shifter. Instead, it uses a clutch pack which facilitates automatic gear shifts fluidly. The clutch pack has plates (discs) that lock at different speed ratios to give your car programmed gear ratios.

• Output Shaft

This is the outward connection between the transmission and the other components in the drivetrain. It is the shaft that drives the drive shaft, which directly powers the wheels.

• Brake Band

Brake bands make the accomplishment of smooth shifting of gears possible. They hold the planetary gears during gear selection and engagement and only release them when the engine rpm and the gear ratio have synced. Its function is akin to what the drum brakes do. The piston tightens the band around the drum hard, exerting a braking power corresponding to the piston's degree of force.

• Oil Pan

Excess transmission fluid goes into the oil pan, which sits at the bottom of your transmission. It is from the pan that the oil pump sucks up the required quantity of fluids that it sends to different parts of the transmission. As a form of protection from grits and shaves, an oil pan typically has an internal or external fluid filter. It also has gaskets around its edges to keep transmission fluid from leaking.

• Valve Body

This component affirms that your Lexus IS250 is genuinely an automatic transmission car. With the aid of sensors, the valve body automatically determines what gets fluids and in what quantity.  

• Axles

These are parts of the components that are outside transmission but within the transmission system. There are two axles: the drive axle and the dead axle.

Drive axles connect to the driveshaft, which means they actively receive the engine's torque via the transmission. Dead axles, on the other hand, do not get any accelerative power. It merely helps to support the car frame and balance.  

Final Thoughts

2015 Lexus IS250 transmission problems are real, and you should always be prepared to tackle them. However, it's not an everyday issue. When you take your car's maintenance services seriously, they're doubtful to occur. 

If you change the transmission fluid as and when due, you replace worn components, and pay attention to any unusual change in the sound from the engine, you can rest assured that your car won't develop any transmission problems.