P0121 on the 2024 Cadillac XT6
A P0121 on your 2024 Cadillac XT6 signals that the ECM has caught an inconsistent throttle position sensor pattern. The data is within voltage limits but doesn't match expected behavior—our detective's analysis points to the throttle body as the focus of investigation.
The 2024 XT6 continues with the 2.0L turbo-four (DI) or 3.6L V6 (port injection). On a new vehicle, software calibration is the primary suspect, though the 2.0T DI engine can produce carbon deposits quickly with city driving.
Symptoms
- Check engine light and possible Reduced Engine Power
- Hesitation on acceleration
- Idle roughness
- Turbo response diminished (2.0T)
- Throttle response delayed
Probable Causes
- ECM software calibration – GM updates for the XT6 platform. Likelihood: 35%
- Carbon deposits – DI turbo carbon accumulation (2.0T). Likelihood: 30%
- Throttle body defect – Manufacturing issue. Likelihood: 20%
- Connector issue – Factory assembly problem. Likelihood: 10%
- Boost or intake leak – Turbo piping (2.0T). Likelihood: 5%
Cost
- All repairs: $0 under warranty
- Out-of-warranty reference: Cleaning $80–$180, replacement $300–$600, software $100–$180
Take It to Cadillac
Your 2024 XT6 is fully covered under Cadillac's 4-year/50,000-mile bumper-to-bumper and 6-year/70,000-mile powertrain warranty. All repairs are at no cost. Cadillac dealers typically provide premium loaner vehicles.
How AutoDetective AI Can Help
AutoDetective's AI analyzes your XT6's engine variant and freeze frame data for a tailored diagnosis. Upload your scan data for a free preview before your dealer visit.