What Does P0121 Mean on a 2024 Kia K5?
P0121 on your 2024 Kia K5 sends our diagnostic team to the throttle position sensor (TPS). The sensor is transmitting voltage within the expected range but with an abnormal pattern that the ECM flags as inconsistent with other engine data.
The 2024 K5 offers the 2.5L MPI four-cylinder (191 hp) or the 1.6L Turbo GDI (180 hp). The MPI engine uses port injection—great for keeping the throttle body clean. The turbo GDI uses direct injection and is more carbon-prone. Both pair with an 8-speed automatic. The TPS is integrated into the electronic throttle body.
Common Symptoms to Watch For
- Check engine light on
- Hesitation during acceleration
- Rough idle
- 8-speed automatic shifting feels off
- Reduced throttle response in Sport mode
- Smart Cruise Control may disengage
Top Causes Ranked by Likelihood
- ECM software calibration (35%) – Current-year calibration refinements. 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; MPI engine least susceptible. Cost: $120–$250 if not covered.
- Intake system leak (5%) – Factory issue. Cost: $0 under warranty.
How Serious Is This Code?
P0121 is medium severity. Your K5 is drivable but may feel less responsive. Warranty makes the fix free. Address this soon.
Diagnostic Path
Kia dealer with KDS diagnostics. Full warranty coverage.
Can You Fix This Yourself?
Kia's 5yr/60k basic + 10yr/100k powertrain (original owner) covers everything. Go to the dealer.
Get a Free AI Diagnosis
MPI or Turbo GDI? AutoDetective's free AI diagnosis provides an engine-specific preliminary analysis.