P0121 on Your 2024 Buick Encore GX
When your 2024 Buick Encore GX sets a P0121, the ECM has detected an inconsistent throttle position sensor signal. The voltage reads within specs but the pattern doesn't match your pedal inputs—our detective has found the first lead in a throttle system investigation.
The 2024 Encore GX uses a 1.2L or 1.3L turbocharged three-cylinder with direct injection. These small-displacement DI turbo engines depend on precise throttle control for boost management and fuel delivery. On a vehicle this new, software calibration and manufacturing quality are the primary diagnostic considerations.
Symptoms
- Check engine light with possible Reduced Engine Power
- Turbo lag or hesitation on acceleration
- Rough idle
- Throttle response feels delayed
- Engine feels underpowered
Top Causes
- ECM software calibration – GM regularly releases refinements for the three-cylinder turbo platform. Likelihood: 35%
- Carbon deposits on throttle body – DI turbo engines accumulate carbon quickly, especially with city driving. Likelihood: 30%
- Throttle body defect – Manufacturing quality issue with the TPS or motor. Likelihood: 20%
- Connector or wiring issue – Factory connection problem in the compact engine bay. Likelihood: 10%
- Boost system interaction – Wastegate or bypass valve anomaly. Likelihood: 5%
Cost
- All repairs: $0 under warranty
- Out-of-warranty reference: Cleaning $80–$150, replacement $250–$450, software $100–$180
Dealer Visit Required
Your 2024 Encore GX is fully covered under GM's 3-year/36,000-mile bumper-to-bumper and 5-year/60,000-mile powertrain warranty. Take it to your Buick dealer for free diagnosis and repair via GDS2. Do not attempt DIY on a warranted vehicle.
How AutoDetective AI Can Help
Upload your scan data to AutoDetective for an AI analysis specific to the Encore GX's three-cylinder turbo platform. Get a free diagnosis before your dealer appointment.