Are you familiar with the Lexus RX400h problems?
The Lexus RX 400h is an impressive piece of engineering from the luxury car manufacturer Lexus in Japan. It was first introduced in 2005 and remains in production today.
The RX 400h is a mid-size luxury crossover SUV that combines the performance of a V6 engine and two electric motors to provide plenty of power for acceleration.
Additionally, the model offers a smooth ride, plenty of interior space, and the latest technology, all while delivering superior fuel economy.
With its sleek styling, advanced safety features, and impressive performance, the Lexus RX 400h is an ideal choice for a luxurious yet efficient ride.
The RX 400h can optimize power delivery for maximum efficiency using continuous variable automatic transmission (CVT), which helps reduce fuel consumption .
The standard all-wheel-drive system also provides excellent traction in all weather and road conditions.
Despite its popularity, the Lexus RX 400h has its share of problems. These range from minor problems to more serious issues affecting the vehicle’s performance and safety.
This article examines the common problems plaguing the Lexus RX 400h and potential solutions to these issues.
Most Common Lexus RX 400h Problems
- Engine Issues
A common problem reported by owners of the Lexus RX 400h is engine trouble. Common engine problems include oil leaks, excessive noise, and mysterious misfires.
Other issues include coolant leaking, the engine running rough and stalling, and a check engine light coming on. If these issues are unchecked, they can lead to more severe problems, such as engine failure .
In some cases, the cause of these problems can be traced back to faulty spark plugs or a clogged fuel filter. To prevent these issues, it is vital to keep a regular maintenance routine.
Common maintenance tasks include oil changes, replacement of air and fuel filters, and checking the coolant levels. Consistent maintenance will, in most cases, solve many of these problems even before they become significant.
- Battery Issues
The Lexus RX 400h has been known to suffer from battery issues. An intermittent electrical connection between the battery and the power management system causes the problem. This can result in a decrease in engine power, stalling, and gas mileage.
The battery’s life expectancy is also reduced, leading to frequent replacements. The issue is especially prevalent in hotter climates as the heat leads to rapid draining of the battery.
In particular, the 2005-2008 Lexus RX 400h models have the most common battery problems reported by owners .
The hybrid battery comprises several cells that gradually lose power over time.
This causes the battery to become weak or even fail, resulting in reduced power and fuel economy. To fix the issue, Lexus recommends replacing the battery and ensuring the connections are properly maintained.
- Leaking Inverter
The hybrid engine’s inverter is a crucial component, and the RX 400h has a history of inverter coolant leaks. The vehicle has experienced several issues related to the inverter, which controls the electric motor and sends power to the wheels.
The most common problem is a leak of oil from the inverter due to seal failure.
This problem has been reported in RX 400h models from 2005 to 2009 and is most commonly seen in vehicles with high mileage. There may be a leaky inverter if you observe the fluid level in the inverter coolant tank dropping or a crusty pink substance surrounding the inverter .
The inverter should be inspected and replaced if necessary to address the issue. You should also replace the seal to prevent future leakage.
Additionally, the battery should be checked and replaced if needed, as a failing battery can strain the inverter and cause additional issues. The inverter is very expensive to replace, and if your vehicle is still under warranty, Lexus should fix it free of charge.
- Power Steering Fluid Leak
A power steering fluid leak was one of the most common problems experienced with the Lexus RX 400h in the 2005-2008 model years .
This issue was caused by a faulty power steering hose and would cause the steering wheel to become stiff and difficult to turn.
It was also reported that the power steering pump would fail, resulting in a loss of power steering control. The manufacturer addressed this issue with a revised power steering hose design.
So, if you own a 2005-2008 model RX 400h, ensure that you have installed the latest power steering hose.
- Transmission Issues
Another common problem with the 2005-2008 Lexus RX 400h was a transmission leak. This was caused by a faulty transmission cooler hose that would leak the vehicle’s transmission fluid. The manufacturer addressed this issue with a revised transmission cooler hose.
In 2009, a recall was issued for the RX 400h because of a transmission issue that could suddenly cause the vehicle to accelerate. The 2013-2018 models were also prone to transmission problems.
This issue was caused by a faulty transmission control module, which could cause the transmission to shift erratically or slip out of gear.
Other transmission issues reported include rough shifting, delayed shifting, and slipping of the transmission. This issue can be addressed by having the transmission replaced.
- Electrical Problems
The Lexus RX 400h has had some electrical system problems reported. Common issues include malfunctioning batteries, power steering, and other electrical components.
Battery failure can be caused by a faulty battery or a defective charging system. A failed power steering pump or electric motor can cause power steering failure. Faulty relays, switches, and wiring can cause other electrical system issues.
Many 2009-2012 Lexus RX 400h model owners reported that the vehicle would suddenly shut off while driving or drain the battery quickly. This issue was caused by a faulty alternator and could be addressed by having the alternator replaced. 
These problems lead to a loss of power or other vehicle malfunctions. A qualified technician must inspect the vehicle to determine the cause of the problem and make the necessary repairs.
Possible solutions to these problems include replacing the faulty components, resetting the computer system, and ensuring the vehicle is adequately charged.
- Braking problems
There have been numerous instances of the RX 400h having braking issues. Some users allege that, in some cases, they must push the brake pedal firmly to activate the brakes entirely or that the system occasionally malfunctions .
The 2006-2008 model years were the most affected.
However, the 2013-2018 models also experienced a faulty brake system. Many owners reported that the brake pedal would become unresponsive or that the brakes would fail prematurely.
This issue was caused by a defective brake system and could be addressed by having the brake system replaced.
You can take the car to the dealer if it’s still under warranty, and they should be able to fix the problem without charging you. Most of the time, a software upgrade can fix the problem. It’s also a good idea to replace the brake pads.
- Suspension Issues
Common suspension problems include clunking or knocking noises from the front suspension, excessive vibration, and poor ride quality. The most frequent issue is the premature wearing of the front suspension struts, which can cause a rattling sound and a feeling of instability when driving.
Another issue is the failure of the sway bar bushings, which can cause the vehicle to sway excessively when cornering.
Additionally, the front lower control arm bushings can become worn out, leading to a rough ride and an increased body roll. Therefore, owners of the Lexus RX 400h should have the suspension checked regularly to ensure that all components are in good working order.
The 2006-2012 models of the Lexus RX 400h were prone to suspension problems. However, the issue was mainly found in the 2006 and 2007 models. Many owners reported that the suspension would fail prematurely, resulting in a bumpy and uncomfortable ride.
- Rear seat rattle problem
The rear seat rattle problem in Lexus RX 400h affects models in the 2005-2008 year range. This problem is primarily noticeable while driving over speed bumps or poorly paved roads .
Poor-fitting of the back seats is the root of this problem since it causes the seat to move around a little.
This movement results in some play in the seat mechanism.
The rattling noise is caused by the loose seat vibrating against the floor. To fix the problem, the rear seat assembly must be secured to the floor either with screws or double-sided tape.
Read Also: Lexus NX300h Problems
The Lexus RX 400h is one of the most popular hybrid vehicles on the market. It offers a great combination of style, comfort, and fuel efficiency. However, despite its popularity, the Lexus RX 400h has its share of problems.
The most common problems experienced with the Lexus RX 400h range from power steering fluid leaks and suspension issues in the earlier model years to faulty brake systems and transmission problems in the later model years.
If you own a Lexus RX 400h, it is crucial to be aware of these common issues and to have them addressed if they arise.
Read Next: Lexus ct200h Problems