What Does P0121 Mean on a 2024 Kia Carnival?
P0121 on your 2024 Kia Carnival directs our investigators to the throttle position sensor (TPS). The sensor is communicating within the expected voltage range but with a pattern the ECM considers abnormal—the data doesn't match calculated values from pedal input, airflow, and engine load.
The 2024 Carnival continues with the 3.5L Lambda III V6 (290 hp) and 8-speed automatic. Port injection keeps the throttle body clean. As a current-year vehicle, calibration and manufacturing issues outweigh wear concerns.
Common Symptoms to Watch For
- Check engine light on
- Hesitation during acceleration
- Rough or unstable idle
- Transmission shifting feels off
- Reduced power with passengers
- Driver assistance features may behave erratically
Top Causes Ranked by Likelihood
- ECM software calibration (35%) – Current-year updates. Cost: $0 under warranty.
- Throttle body manufacturing defect (30%) – Factory defect. Cost: $0 under warranty.
- Wiring or connector defect (20%) – Assembly variability. Cost: $0 under warranty.
- Carbon buildup (10%) – Unlikely at low mileage. Cost: $150–$300 if not covered.
- Intake system leak (5%) – Factory issue. Cost: $0 under warranty.
How Serious Is This Code?
P0121 is medium severity. Your family van needs flawless throttle response. Warranty covers everything. Fix this soon.
Diagnostic Path
Kia dealer with KDS diagnostics. Full warranty coverage.
Can You Fix This Yourself?
Full warranty: 5yr/60k basic + 10yr/100k powertrain. Dealer visit is completely free.
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