What P0121 Means on Your 2024 Acura RDX
A P0121 code on your 2024 Acura RDX means the ECM has flagged an abnormal throttle position sensor signal. The voltage stays in range but the pattern is erratic—like a detective reviewing camera footage where the images are clear but the sequence doesn't make sense. The throttle body needs investigation.
The 2024 RDX continues with the 2.0L VTEC turbocharged four-cylinder with direct injection. This proven powertrain delivers 272 hp through a 10-speed automatic. The DI-only fuel system is inherently more susceptible to carbon accumulation, but on a vehicle this new, software and manufacturing quality are primary considerations.
Symptoms
- Check engine light on
- Turbo lag that seems excessive
- Hesitation on acceleration
- Idle quality slightly degraded
- Throttle response feels less crisp
Probable Causes
- ECM software calibration – Honda/Acura regularly releases powertrain software refinements. Most likely cause on a new vehicle. Likelihood: 35%
- Carbon deposits – DI turbo engines can accumulate throttle body deposits quickly with short-trip city driving. Likelihood: 30%
- Throttle body defect – Manufacturing quality issue with the TPS or actuator motor. Likelihood: 20%
- Wiring or connector issue – Factory connector seating problem. Likelihood: 10%
- Turbo system interaction – Boost pressure anomaly affecting throttle body. Likelihood: 5%
Repair Costs
- All repairs: $0 under warranty
- Out-of-warranty reference: Cleaning $100–$180, replacement $350–$600, software $100–$200
Dealer Is the Only Option
Your 2024 RDX is fully covered under Acura's 4-year/50,000-mile basic warranty and 6-year/70,000-mile powertrain warranty. Take it to the Acura dealer for no-cost diagnosis and repair. The dealer will use Honda Diagnostic System to analyze the throttle body, apply software updates, and replace the throttle body if needed—all at zero cost.
How AutoDetective AI Can Help
Upload your scan data to AutoDetective before the dealer visit. Our AI will analyze the freeze frame data to determine whether you're likely dealing with a software or hardware issue.