P0121 on Your 2024 Cadillac XT5
When your 2024 Cadillac XT5 triggers P0121, the ECM has detected that the throttle position sensor signal doesn't follow expected patterns. The voltage is in range but the behavior is inconsistent—our detective has flagged the throttle body for closer examination.
The 2024 XT5 continues with the 2.0L turbo-four (DI) or 3.6L V6 (port injection). On a vehicle this new, software calibration and manufacturing quality take priority over wear-related carbon buildup, though the 2.0T DI model can accumulate deposits quickly with city driving.
Symptoms
- Check engine light and possible Reduced Engine Power
- Hesitation on acceleration
- Idle roughness
- Turbo feels sluggish (2.0T)
- Throttle response delayed
Top Causes
- ECM software calibration – GM refinements for the XT5 platform. Likelihood: 35%
- Carbon deposits – DI turbo carbon from city driving (2.0T). Likelihood: 30%
- Throttle body defect – Manufacturing issue. Likelihood: 20%
- Connector issue – Factory assembly problem. Likelihood: 10%
- Intake system leak – Turbo piping or gasket. Likelihood: 5%
Cost
- All repairs: $0 under warranty
- Out-of-warranty reference: Cleaning $80–$180, replacement $300–$600, software $100–$180
Dealer Visit
Your 2024 XT5 is fully covered under Cadillac's 4-year/50,000-mile bumper-to-bumper and 6-year/70,000-mile powertrain warranty. Take it to the Cadillac dealer for complimentary repair. The dealer uses GDS2 for diagnosis and can apply any available software updates.
How AutoDetective AI Can Help
Upload your scan data to AutoDetective for a free AI diagnosis that accounts for your XT5's specific engine variant.