What Does P0121 Mean on a 2022 Jeep Grand Wagoneer?
A P0121 code on your 2022 Jeep Grand Wagoneer tells you the PCM has detected an abnormal pattern from the throttle position sensor (TPS). The voltage is within range, but the signal behavior doesn't match what the computer expects based on your accelerator pedal input. Your Grand Wagoneer's system has flagged the throttle for investigation.
The 2022 Grand Wagoneer runs the 6.4L Hemi V8 (471 hp) with port fuel injection. This massive engine uses electronic throttle control with the TPS integrated into the throttle body. Port injection generally keeps the throttle body cleaner than direct injection, but at 2-4 years old, the combination of carbon accumulation and possible software/hardware issues are viable suspects.
Top Causes of P0121 on the 2022 Grand Wagoneer
- Carbon buildup on throttle body – Even port injection accumulates deposits over time. Likelihood: 35%
- PCM software calibration – First-generation vehicle; Jeep has released updates. Likelihood: 25%
- Throttle body defect – Internal TPS issue. Likelihood: 20%
- Connector or wiring issue – Corrosion or loose connection. Likelihood: 15%
- Intake vacuum leak – Large V8 intake system has many potential leak points. Likelihood: 5%
Symptoms You May Notice
- Check Engine Light on
- Rough or inconsistent idle
- Hesitation during acceleration
- Reduced engine power from the 6.4L V8
- Traction control or ESC warnings
- Reduced towing confidence
How Serious Is This Code?
P0121 is medium severity. Your 2022 Grand Wagoneer remains drivable, but throttle irregularity on a vehicle this large and powerful should be addressed promptly. Fix it soon—within 1-2 weeks. The 6.4L V8 relies on precise throttle control for its MDS (Multi-Displacement System) cylinder deactivation to function properly.
Diagnostic Steps
- Scan for codes and freeze frame data
- Inspect throttle body for carbon deposits
- Monitor TPS voltage: ~0.5V idle, smooth sweep to ~4.5V WOT
- Check throttle body connector for secure fit and clean pins
- Inspect wiring harness for damage
- Check for TSBs at the dealer using wiTECH
Estimated Repair Costs
- Under warranty: $0 (3-year/36,000-mile basic warranty likely still active)
- Throttle body cleaning: $120–$250
- Throttle body replacement: $400–$700
- Wiring repair: $150–$350
Can You DIY This Fix?
DIY feasibility is low to moderate. The Grand Wagoneer is a premium vehicle likely still under warranty—check with your dealer first. The 3-year/36,000-mile basic warranty may still cover the repair, and the 5-year/60,000-mile powertrain warranty is active. Given the vehicle's price point and available warranty, dealer repair is the recommended path. If out of warranty, the large engine bay provides good access to the throttle body for DIY cleaning.