P0121 on Your 2022 GMC Acadia: What's Going On?
A P0121 code on your 2022 GMC Acadia means the engine control module has flagged an inconsistency in the throttle position sensor signal. The voltage readings are within normal boundaries, but the pattern doesn't match what the ECM expects based on your pedal input—like a detective finding fingerprints at a crime scene that belong to the right person but are in all the wrong places.
The 2022 Acadia uses GM's 2.0L turbocharged four-cylinder or the 3.6L V6, both with fully electronic throttle control. The TPS is built into the throttle body and uses redundant signal circuits (TPS1 and TPS2) that the ECM cross-checks continuously.
Symptoms to Watch For
- Check engine light with possible Reduced Engine Power warning
- Intermittent hesitation when pressing the gas pedal
- Rough or hunting idle
- Momentary loss of throttle response
- Engine may feel sluggish under load
Most Likely Causes
- Carbon deposits on throttle plate and bore – The 2.0L turbo's direct injection system is particularly prone to carbon buildup that creates drag on the throttle plate. Even the 3.6L V6 can accumulate deposits over time. Likelihood: 45%
- Failing throttle body assembly – The internal DC motor or integrated TPS wears down, producing erratic signals. Likelihood: 25%
- Connector corrosion or damaged wiring – The throttle body connector sits in a high-heat area and can develop oxidation on the pins. Likelihood: 15%
- Software update needed – GM has released recalibrations for throttle response mapping on certain 2022 Acadia builds. Likelihood: 10%
- Post-throttle body air leak – Cracked intake manifold gasket or loose PCV hose allowing unmetered air. Likelihood: 5%
What Will Repairs Cost?
- Throttle body cleaning: $80–$150 (shop) / $10–$20 (DIY)
- Throttle body replacement: $300–$550 parts and labor
- Wiring/connector repair: $100–$250
- ECM recalibration: $100–$180 dealer visit
Can You DIY This?
Your 2022 Acadia may still be under GM's 3-year/36,000-mile bumper-to-bumper warranty depending on mileage. Check your warranty status first. If out of warranty, throttle body cleaning is a moderate DIY job—remove the intake duct, disconnect the electrical connector, and clean with throttle body cleaner. After cleaning, a throttle relearn procedure is required: disconnect the battery for 30 minutes, reconnect, then start the engine and let it idle for 15 minutes without touching the gas pedal.
How AutoDetective AI Can Help
Run your scan data through AutoDetective's AI diagnostic engine. It analyzes your 2022 Acadia's specific engine variant and mileage to rank the most probable causes and estimate repair costs in your area.