What Does P0121 Mean on a 2023 Jeep Gladiator?
A P0121 code on your 2023 Jeep Gladiator indicates the PCM has caught the throttle position sensor (TPS) sending a signal that doesn't match expected patterns. The voltage is within range but behaves erratically relative to your driving inputs. On a relatively new Gladiator, this warrants a dealer visit.
The 2023 Gladiator (JT) runs the 3.6L Pentastar V6 with port fuel injection as standard. Electronic throttle control integrates the TPS into the throttle body. On a vehicle with 1-3 years of use, both carbon buildup and software/hardware issues are viable suspects—though carbon is less likely at lower mileage.
Top Causes of P0121 on the 2023 Gladiator
- PCM software calibration – A reflash may resolve throttle mapping issues. Likelihood: 30%
- Carbon buildup – Possible even at moderate mileage, especially with towing and off-road use. Likelihood: 25%
- Throttle body defect – Internal TPS fault. Likelihood: 20%
- Connector or wiring issue – Off-road exposure or factory assembly issue. Likelihood: 20%
- Intake leak – Loose clamp or deteriorated boot. Likelihood: 5%
Symptoms You May Notice
- Check Engine Light on
- Inconsistent or rough idle
- Hesitation during acceleration
- Reduced towing confidence
- ESC warnings
- Cruise control may not engage
How Serious Is This Code?
P0121 is medium severity. Your 2023 Gladiator remains drivable, but any throttle irregularity on a truck used for towing and off-roading deserves prompt attention. Address it soon—schedule a dealer appointment within the week. Warranty should cover the repair.
Diagnostic Steps
- Visit your Jeep dealer—warranty applies
- Dealer uses wiTECH for comprehensive diagnostics
- Check for TSBs and PCM software updates
- Inspect throttle body for carbon buildup and connector integrity
- Monitor live TPS data during driving
- If off-road accessories are installed, check for electrical interference
Estimated Repair Costs
- Under warranty: $0 (covered by 3-year/36,000-mile basic warranty)
- PCM reflash: $0 under warranty
- Throttle body cleaning (if out of warranty): $100–$200
- Throttle body replacement (if out of warranty): $350–$600
Should You DIY This?
DIY feasibility is low—not due to difficulty, but because your 2023 Gladiator is under Stellantis' 3-year/36,000-mile basic warranty and 5-year/60,000-mile powertrain warranty. Let the dealer handle it at no charge. If a PCM update is needed, only the dealer's wiTECH system can perform the reflash.