What P0174 Means on Your 2024 Lexus RX
A P0174 code on your 2024 Lexus RX indicates the engine management system has detected a lean condition on Bank 2. The redesigned 2024 RX offers the 2.4L turbocharged four-cylinder (275 hp in the RX 350) and the 2.5L four-cylinder hybrid (246 combined hp in the RX 350h and RX 450h+). Both are inline-four engines with a single bank, so P0174 means the lean correction has exceeded programmed thresholds.
The 2024 RX is a completely new design with a new engine lineup. Under full warranty, any lean-condition issues should be handled by your Lexus dealer.
Symptoms
- Check engine light on
- Rough or unsteady idle
- Reduced power and boost response (RX 350)
- Decreased fuel economy
- Hesitation during acceleration
- Possible surging at constant speed
Common Causes
- Boost or Vacuum Leak (35% likelihood) – The RX 350's 2.4T has turbo charge piping that can have factory assembly issues. The hybrid models have standard intake components to check.
- MAF Sensor Issue (25% likelihood) – Factory defect or early contamination of the mass airflow sensor.
- Fuel System Problem (20% likelihood) – Direct injection injector issue or fuel pressure defect.
- Software Calibration (20% likelihood) – As a new platform, Toyota/Lexus may have released ECU updates for fuel trim optimization.
Diagnosis
- Dealer visit – The 2024 RX is under full Lexus warranty. Take it to the dealer.
- Check TSBs – Lexus may have Technical Service Bulletins for new model lean conditions.
- Comprehensive scan – The dealer's Lexus Techstream diagnostic system provides detailed data.
- Component testing – MAF, boost system, fuel system analysis.
Repair Costs
- Covered under Lexus warranty.
- Out-of-pocket estimates: Boost/vacuum leak $100–$450, MAF $150–$380, fuel system $250–$600, software update $0–$200.
The 2024 Lexus RX is covered by a 4-year/50,000-mile basic warranty and 6-year/70,000-mile powertrain warranty. Lexus's warranty is among the most comprehensive in the luxury segment.
Let Lexus Handle It
With premium warranty coverage and a brand-new engine platform, the Lexus dealer is the clear choice. They have Techstream diagnostic software, factory training on the new engines, and use genuine Lexus parts. The repair will be free and properly documented in your vehicle's service history.
Prevention
- Follow Lexus's recommended maintenance schedule
- Use premium fuel as recommended
- Report any drivability changes to the dealer promptly
- Keep all service records
- Maintain regular dealer service visits