P0121 on Your 2022 Acura RDX: Tracking Down the Issue
When your 2022 Acura RDX sets a P0121, the ECM has identified that the throttle position sensor signal doesn't follow expected patterns. The voltage is within range but behaves erratically—our detective has spotted an inconsistency between what your pedal commands and what the throttle body reports.
The 2022 RDX is powered exclusively by a 2.0L VTEC turbocharged four-cylinder with direct injection, producing 272 hp. This engine's DI fuel system makes it inherently more susceptible to carbon-related throttle body issues than Honda's port-injection engines. The electronic throttle body uses integrated dual TPS signals.
Symptoms
- Check engine light illuminated
- Turbo response feels sluggish
- Hesitation during acceleration from a stop
- Idle roughness or surging
- Throttle pedal may feel momentarily unresponsive
Most Probable Causes
- Carbon buildup on throttle body – The 2.0L turbo DI engine is a prime candidate for carbon accumulation on the throttle plate and bore. City driving and short trips accelerate this. Likelihood: 50%
- Throttle body assembly failure – Internal TPS or motor wear in the electronic throttle body. Likelihood: 20%
- ECM software update – Honda/Acura may have released recalibrations for the RDX's throttle management. Likelihood: 15%
- Wiring or connector issue – Corrosion or loose pin at the throttle body connector. Likelihood: 10%
- Boost system interaction – Wastegate or turbo bypass valve issue affecting throttle body pressure. Likelihood: 5%
Repair Costs
- Throttle body cleaning: $100–$180 (shop) / $10–$25 (DIY)
- Throttle body replacement: $350–$600 parts and labor
- Wiring repair: $100–$250
- ECM update: $100–$200 (dealer)
Warranty & DIY
Your 2022 RDX may still be within Acura's 4-year/50,000-mile basic warranty depending on mileage. The 6-year/70,000-mile powertrain warranty should still apply. Check with your dealer first. If out of basic warranty, throttle body cleaning is moderate difficulty on the 2.0L turbo—remove the intake tube from the turbo to the throttle body, disconnect the connector, and clean. After cleaning, perform the Honda idle relearn: key ON for 10 seconds, start the engine, idle for 10 minutes.
How AutoDetective AI Can Help
AutoDetective's AI understands the RDX's 2.0L turbo DI engine's carbon buildup tendencies. Upload your scan data for a diagnosis that differentiates between carbon, sensor failure, and software issues.