10 Common 2003 Lexus GX470 Problems (and Easy Fixes)

Owning a car like the 2003 Lexus GX470 is exciting, but every vehicle can develop issues over time.

From minor wear and tear to common maintenance needs, understanding these problems can save you time and money.

Here, we’ll explore 10 common 2003 Lexus GX470 problems you might face, along with simple fixes to keep your ride running smoothly.

Table of Contents

2003 Lexus GX470 Problems (Short Overview)

The GX470 is built on the same platform as the famously reliable Toyota 4Runner, which gives it a strong foundation.

However, certain components are more prone to wear and tear.

This section will explore the top ten issues reported by owners and mechanics.

1. Cracked Dashboard

Cause:

Prolonged exposure to UV rays from the sun breaks down the dashboard’s plastic and vinyl compounds.
Extreme temperature fluctuations, from hot days to cold nights, cause the material to expand and contract.
This constant stress eventually leads to the material becoming brittle and cracking under pressure.
The use of harsh cleaning chemicals can also dry out the dashboard, accelerating the process.

Fixes:

For minor cracks, you can use a vinyl and leather repair kit to fill and seal the damage.
For a more seamless and durable solution, installing a custom-fit dashboard cover is an excellent option.
These covers are designed to fit perfectly over your existing dash, hiding the cracks completely.
To prevent future cracking, regularly apply a high-quality UV protectant spray to your dashboard.

2. Leaking Transfer Case Actuator

Cause:

The seals and O-rings inside the actuator are made of rubber, which can degrade and harden over time.
Constant exposure to heat from the transmission and exhaust system accelerates this degradation.
This causes the seals to lose their flexibility, creating gaps that allow gear oil to leak out.
In some cases, the actuator housing itself can develop small cracks, though this is less common.

Fixes:

The most common fix involves replacing the faulty seals and O-rings within the actuator.
This requires removing the actuator from the transfer case, which can be a complex job.
It’s a good idea to drain the transfer case fluid before starting the repair.
If the housing is damaged or the actuator motor has failed, you will need to replace the entire unit.

3. Seized Front Brake Calipers

Cause:

The caliper pistons, which push the brake pads, can become corroded due to moisture and road salt.
This corrosion prevents the pistons from retracting smoothly into the caliper housing after braking.
The rubber dust boots that protect the pistons can tear, allowing debris and water to enter.
This contamination accelerates corrosion and causes the pistons to seize in place.

Fixes:

In some cases, you can rebuild the caliper by removing, cleaning, and lubricating the pistons.
This process also involves replacing the rubber seals and dust boots with a rebuild kit.
However, the more common and often easier solution is to replace the entire seized caliper.
Always replace brake calipers in pairs (both front calipers) to ensure even braking performance.

4. Secondary Air Injection Pump Failure

Cause:

The pump’s electric motor can wear out over time, leading to complete failure.
Moisture can get into the system, causing corrosion within the pump and the air switching valves.
The foam filters inside the pump can disintegrate, sending debris into the valves and causing them to stick.
This blockage prevents the system from operating correctly and triggers diagnostic trouble codes.

Fixes:

The first step is to diagnose the system to confirm if the pump or a valve is the issue.
If the pump has failed, you will need to replace it with a new unit.
Sometimes, only the air switching valves are stuck and can be cleaned or replaced independently.
There are also bypass kits available that trick the computer, but check local emissions laws first.

5. Suspension Air Bag Leaks

Cause:

The rear air bags are made of a flexible rubber material that becomes dry and brittle with age.
Constant flexing and exposure to the elements cause tiny cracks to form in the rubber.
These cracks eventually grow large enough to let air leak out, preventing the system from holding pressure.
Debris and road grit can also get trapped in the folds of the rubber, causing abrasive wear.

Fixes:

The most direct fix is to replace the leaking air bags with new OEM or aftermarket parts.
Replacing them is a manageable DIY job for those with mechanical experience.
A popular and more permanent alternative is to convert the rear suspension to standard coil springs.
This coil conversion kit eliminates the air suspension system entirely, providing a reliable, though less adjustable, ride.

6. Power Steering Fluid Leak

Cause:

The seals inside the power steering rack can wear out over time, allowing fluid to leak.
The rubber power steering hoses can become hard and brittle, leading to cracks at the connection points.
Clamps on the hoses can loosen, creating a slow drip that worsens over time.
Corrosion on the metal lines of the steering rack can also create pinhole leaks.

Fixes:

If the leak is from a hose, replacing the specific hose is the most straightforward solution.
Make sure to use new O-rings and clamps when installing the new hose.
If the steering rack itself is leaking, it will likely need to be replaced or professionally rebuilt.
Regularly check your power steering fluid level and top it off to prevent pump damage while addressing the leak.

7. Knock Sensor Failure

Cause:

The sensors are located under the engine’s intake manifold, where they are exposed to intense heat.
This constant heat can cause the sensor’s internal electronics to fail over time.
The wiring harness connected to the sensors can also become brittle and crack from the heat cycles.
A coolant leak from the valley plate above the sensors can drip down and short them out.

Fixes:

Replacing the knock sensors requires removing the entire intake manifold to access them.
This is an intensive job, so it’s highly recommended to replace both sensors at the same time.
You should also replace the wiring harness that connects to the sensors while you are in there.
It’s also wise to replace the intake manifold gaskets during this repair to prevent future vacuum leaks.

8. Thumping Noise from the Driveshaft

Cause:

The driveshaft has a slip yoke that allows it to change length as the suspension moves up and down.
The grease inside this slip yoke can dry out or get displaced over time.
Without proper lubrication, the yoke can bind and release suddenly during acceleration or braking.
This binding and releasing action is what creates the distinct thumping noise.

Fixes:

This is a relatively easy and inexpensive fix that involves lubricating the driveshaft’s zerk fittings.
You will need a grease gun filled with the appropriate type of moly-fortified grease.
Locate the zerk fittings on the driveshaft and pump grease into them until you see the slip yoke boot swell slightly.
Performing this lubrication every oil change can prevent the problem from returning.

9. Head Gasket Failure

Cause:

Engine overheating is the primary cause of head gasket failure, as excessive heat can warp the cylinder head.
This warping creates a gap that the head gasket can no longer seal effectively.
Age and high mileage can also cause the gasket material itself to degrade and fail.
An improperly functioning cooling system (e.g., a bad radiator or water pump) puts extra stress on the gasket.

Fixes:

Replacing a head gasket is a very complex and labor-intensive repair that is best left to a professional mechanic.
The process involves removing the cylinder head, having it checked for warpage, and replacing the gasket.
It is critical to also address the root cause of the failure, such as fixing any cooling system issues.
Due to the high cost, it’s important to weigh the repair cost against the vehicle’s value.

10. Frozen Navigation/Infotainment Screen

Cause:

Software glitches are a common cause of the screen freezing up.
The internal computer that runs the infotainment system can fail due to age or electrical issues.
Extreme temperatures, either hot or cold, can sometimes affect the screen’s performance temporarily.
In some cases, the touchscreen’s digitizer, which registers touch inputs, can wear out.

Fixes:

The simplest first step is to try resetting the system by disconnecting the vehicle’s battery for about 15 minutes.
If the issue persists, a dealership may be able to perform a software update to fix known bugs.
If the hardware has failed, the entire navigation unit may need to be repaired or replaced.
There are third-party services that specialize in repairing these units, which can be cheaper than a full replacement.

FAQs

Is the 2003 Lexus GX470 a reliable vehicle?

Yes, the 2003 Lexus GX470 is widely considered a very reliable vehicle, often lasting well over 200,000 miles with proper maintenance. Its V8 engine and drivetrain are known for their durability.

What is the most expensive problem to fix on a GX470?

Head gasket failure is typically the most expensive issue to repair due to the high labor costs involved in accessing and replacing the gasket.

How often should I service my GX470’s driveshaft?

It’s a good practice to lubricate the driveshaft’s zerk fittings with every oil change (roughly every 5,000 to 7,500 miles) to prevent the common “thumping” issue.

Can I replace the air suspension with regular springs?

Yes, converting the rear air suspension to a traditional coil spring setup is a very popular and reliable modification that eliminates the risk of future air bag leaks.

How do I know if my front brake calipers are seized?

Signs of a seized caliper include the vehicle pulling to one side, a noticeable burning smell after driving, and one wheel being significantly hotter than the others.