What Does P0121 Mean on Your 2020 Dodge Charger?
A P0121 code on your 2020 Dodge Charger tells the PCM that the throttle position sensor signal is within voltage range but behaving erratically. The signal pattern doesn't match the expected correlation with your accelerator pedal position—a key clue in our investigation that something is disrupting the throttle body's communication with the engine computer.
The 2020 Charger comes with either the 3.6L Pentastar V6 or one of the Hemi V8 options (5.7L, 6.4L, or the supercharged 6.2L Hellcat). All use drive-by-wire electronic throttle control. The Pentastar and Hemi V8s use port fuel injection, which generally keeps the throttle body cleaner than direct-injection engines, but carbon from PCV vapors still accumulates over time.
Symptoms You'll Notice
- Check engine light illuminated
- Hesitation or stumble when pressing the gas
- Rough or fluctuating idle
- Loss of throttle response—pedal feels dead momentarily
- MDS (Multi-Displacement System) may not engage properly on Hemi engines
Top Causes Ranked
- Carbon buildup on throttle body – PCV system vapors coat the throttle plate and bore over time. At 4–6 years old with likely 50,000–80,000+ miles, this is the primary suspect. Likelihood: 45%
- Throttle body assembly failure – The integrated TPS motor or sensor wears internally. Stellantis (then FCA) throttle bodies have a known service life on this platform. Likelihood: 25%
- Wiring harness or connector corrosion – The Charger's large engine bay generates significant heat, especially the Hemi variants. Connector pins can corrode. Likelihood: 15%
- Vacuum or intake leak – Deteriorated intake manifold gaskets or cracked PCV hoses. Likelihood: 10%
- PCM calibration issue – Outdated throttle adaptation tables. Likelihood: 5%
Estimated Repair Costs
- Throttle body cleaning: $80–$150 (shop) / $10–$20 (DIY)
- Throttle body replacement: $250–$500 parts and labor
- Wiring repair: $100–$250
- Intake gasket/hose repair: $150–$350
DIY Feasibility: High
Your 2020 Charger is out of the 3-year/36,000-mile basic warranty but may be within the 5-year/60,000-mile powertrain warranty. Check your mileage. The federal emissions warranty (8 years/80,000 miles) may also apply. For DIY, the throttle body is very accessible on both the Pentastar and Hemi engines. Clean with throttle body cleaner, reassemble, then use a scan tool to perform a throttle body relearn (or use wiTECH if available). A battery disconnect for 20–30 minutes followed by a 15-minute idle can also reset adaptations.
How AutoDetective AI Can Help
Upload your scan data to AutoDetective and our AI will analyze your Charger's specific engine, mileage, and freeze frame data to pinpoint the most likely cause. Get a diagnosis before spending on parts.