What Does P0121 Mean on a 2024 Hyundai Elantra?
When P0121 appears on your 2024 Hyundai Elantra, our diagnostic investigation reveals the throttle position sensor (TPS) is communicating within the expected voltage range but with an abnormal performance pattern. The ECM sees readings that don't align with accelerator pedal input, airflow data, and calculated engine load.
The 2024 Elantra offers the 2.0L MPI four-cylinder (147 hp) or the 1.6L Turbo GDI (201 hp in N-Line). MPI (Multi-Point Injection) is essentially port injection—great for keeping the throttle body clean. The 1.6L Turbo uses GDI (Gasoline Direct Injection), which is more carbon-prone. Both pair with either a CVT or 7-speed DCT depending on trim. The TPS is integrated into the electronic throttle body.
Common Symptoms to Watch For
- Check engine light on
- Hesitation during acceleration
- Rough or unstable idle
- CVT or DCT feels jerky or unresponsive
- Reduced throttle response
- Smart Cruise Control may not respond smoothly
Top Causes Ranked by Likelihood
- ECM software calibration (35%) – Current-year vehicles commonly need calibration refinements. Cost: $0 under warranty.
- Throttle body manufacturing defect (30%) – A factory defect in the throttle body or TPS element. Cost: $0 under warranty.
- Wiring or connector defect (20%) – Assembly variability. Cost: $0 under warranty.
- Carbon buildup on throttle body (10%) – Unlikely at low mileage, though the 1.6L Turbo GDI is more susceptible. Cost: $120–$250 if not covered.
- Intake system leak (5%) – Factory clamp or gasket issue. Cost: $0 under warranty.
How Serious Is This Code?
P0121 is medium severity. Your Elantra is drivable, but any throttle issue is noticeable on a compact car. Address this soon—warranty makes it free.
Diagnostic Path
Take your 2024 Elantra to a Hyundai dealer. They'll use GDS (Hyundai's diagnostic system) to monitor TPS data and check for calibration updates.
Can You Fix This Yourself?
Your 2024 Elantra is covered by Hyundai's industry-leading warranty: 5yr/60k basic + 10yr/100k powertrain (original owner). Everything is covered—take it to the dealer.
Get a Free AI Diagnosis
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