P0121 Explained: Your 2024 Lexus ES
A P0121 code on your 2024 Lexus ES signals that the ECM has detected an abnormal throttle position sensor pattern. The TPS voltage is within normal limits but doesn't track your pedal inputs consistently—our detective notes this as the first lead in investigating the throttle system.
The 2024 ES is available as the ES 250 (2.5L four-cylinder AWD), ES 350 (3.5L V6 with D-4S dual injection), and ES 300h hybrid. All ride on Toyota's TNGA-K platform. The ES 350's D-4S system uses both port and direct injection, providing a natural cleaning effect on the intake valves and throttle body area.
Symptoms You May Notice
- Check engine light on
- Subtle hesitation during light throttle inputs
- Idle quality slightly diminished
- Throttle response feels less precise than usual
- Possible brief power delivery inconsistency
Probable Causes
- ECM software calibration – On a new vehicle, a software update is the most likely fix. Lexus regularly refines throttle response mapping. Likelihood: 35%
- Carbon deposits from short-trip driving – Even with D-4S, city-only driving can produce throttle body deposits relatively quickly. Likelihood: 30%
- Throttle body component defect – Factory quality issues with the TPS or actuator motor. Likelihood: 20%
- Connector or wiring issue – Assembly line connector not fully seated. Likelihood: 10%
- Intake air leak – Loose hose clamp or gasket misalignment. Likelihood: 5%
Cost to Fix
- All repairs: $0 under warranty
- Out-of-warranty reference: Cleaning $100–$180, replacement $350–$600, software $100–$200
Lexus Dealer Is the Answer
Your 2024 ES is fully covered under Lexus's 4-year/50,000-mile basic warranty. Take it to your Lexus dealer for diagnosis and repair at no cost. The dealer will use Techstream to analyze the throttle system, apply any software updates, and replace hardware if necessary. Lexus's complimentary service includes a loaner vehicle while your car is being repaired.
How AutoDetective AI Can Help
Before your dealer visit, run your scan data through AutoDetective. Our AI will analyze your 2024 ES's specific powertrain and freeze frame data to preview the likely diagnosis.