Lexus NX 350h Reliability

The NX 350h has a widespread 12V battery drain issue affecting multiple owners worldwide. The DC-DC converter turns off nearly all the time the car is in DRIVE, meaning the 12V battery never gets properly charged. This causes rapid drain when parked or using accessories - some owners report the battery dying in 10-30 minutes while adjusting settings or listening to the radio. This is particularly problematic because electronic door handles require 12V power, potentially trapping occupants. The issue appears systematic across NX450h+, RX450h, and RAV4 PHEV platforms. Dealers have struggled to diagnose and resolve this problem. The OE battery is only 563 CCA; aftermarket AGM batteries with 600+ CCA are recommended. Parasitic draw while parked is significant - the Lexus app reportedly keeps ECUs active, draining the battery faster.

Approximately 25% of Lexus owners report infotainment issues within the first three years according to J.D. Power. The NX central touchscreen can freeze or respond slowly, particularly on early 2022-2023 models. Common trigger: connecting two Bluetooth devices configured as audio players simultaneously causes continuous reboot cycles. Manual fix: turn on ACC, turn off radio, press and hold volume knob until UI restarts. Software bugs in the Lexus Interface system persist despite being reported for over 2 years. CarPlay and Android Auto connectivity problems are frequently reported. TSB available for head unit software update on 2022 models. Most issues resolve with software updates or Bluetooth device management, but some units require replacement (€150-400 in the UK).

Multiple owners describe the NX 350h as having "more rattles and squeaks than any car I've ever owned" - surprising for a luxury vehicle. Common problem areas: driver's side dashboard (rattle on rough surfaces), rearview mirror housing, passenger door, and plastic shield under driver's seat. One 2025 NX350h owner reported Lexus service disassembled the dashboard three times, wrapping everything in felt, but the rattle returned after 3-4 weeks. Owners note significantly worse build quality compared to previous Lexus models like the GS. Some vehicles show rattles even at 500 miles. North American market cars particularly affected, with reports of unevenly installed door panels and interior glass trim cracks. Dealers struggle to permanently resolve these issues even under warranty. This is inconsistent with Lexus's luxury reputation and historical build quality standards.

The NX 350h comes standard with run-flat tires (235/60R18 or 235/50R20 depending on trim), which generate significantly more road noise than standard tires. Many owners report they "couldn't stand the noise" after 10,000 miles and replaced all tires with conventional ones like Michelin CrossClimate 2. The noise is particularly noticeable in town driving, though less prominent on highways. One owner described run-flat noise as comparable to winter tires - "some don't mind it, others would rather rip their ears off." Run-flats also stiffen the ride quality. Replacement with conventional tires immediately reduces cabin noise. Cost to replace all four with premium non-run-flat tires: €700-1,100 depending on brand. This is almost a mandatory upgrade for comfort. Note: switching to conventional tires means no spare - consider purchasing a spare tire kit (€300-400).

In freezing weather, the rubber button on the electronic door handle becomes frozen solid and cannot be pushed to open the door, even though the car is unlocked. This affects both NX and RX models with electronic door handles. Temporary fix: pour warm (not hot) water over the handle or warm the door area. Long-term solution: some dealers replace the door handle assembly entirely. One Toronto dealership replaced door handles as warranty work. This issue is particularly problematic combined with 12V battery drain, as a dead battery prevents using the backup key. Fuel door can also freeze shut, making refueling impossible. Early production models (2022) more affected; later builds reportedly improved. Prevention: lubricate door locks with silicone spray. Handle assembly replacement costs €200-600 depending on labor rates.

The A25A-FXS engine's EGR (Exhaust Gas Recirculation) cooler is known to be faulty and can crack at any mileage. When it fails, coolant leaks into the combustion chamber and burns, producing white smoke from the tailpipe and rapid coolant level drop. This is less common on hybrids since the engine runs less at high RPM, reducing thermal stress. Other EGR-related issues include valve sticking and carbon buildup. The D4-S fuel injection system is sensitive to fuel quality - using low-quality fuel or neglecting fuel filter changes causes injector clogging requiring expensive cleaning. Despite these concerns, the A25A-FXS is considered one of the most durable hybrid units available, with estimated longevity around 180,000 miles or more. Regular maintenance and quality fuel significantly reduce EGR and injector problems.

Some NX owners report brake pedal feels spongy or braking power is reduced, often linked to faulty brake actuators or brake fluid reservoir issues. More concerning: some vehicles suddenly stop while reversing at low speeds with the brake warning light illuminated - this requires immediate dealer inspection. TSB L-SB-0034-24 addresses system malfunction warnings and brake lights on 2022-2024 NX models without diagnostic codes. The hybrid regenerative braking system can make diagnosing traditional brake issues more complex. Brake pad replacement costs €150-300 per axle, rotors €300-750 for all four. Lexus recommends rotor replacement by 70,000 km but this varies based on driving style. The blended braking system (regenerative + friction) typically extends brake life compared to conventional vehicles.