What Does P0121 Mean on a 2021 Jeep Cherokee?
A P0121 code on your 2021 Jeep Cherokee tells you the PCM has found that the throttle position sensor (TPS) signal pattern doesn't match expected behavior. The voltage is within range, but the readings don't correlate properly with your pedal input. Your Cherokee's onboard detective system has flagged a throttle anomaly worth investigating.
The 2021 Cherokee (KL) offers the 2.4L Tigershark four-cylinder or 3.2L Pentastar V6, both with port fuel injection. Electronic throttle control integrates the TPS into the throttle body. At 3-5 years old, the cause could be either carbon accumulation or early hardware/software issues.
Top Causes of P0121 on the 2021 Cherokee
- Carbon buildup on throttle plate – Accumulates even with port injection over 3-5 years. Likelihood: 40%
- Throttle body assembly issue – Internal TPS fault or early wear. Likelihood: 25%
- PCM software calibration – A dealer reflash may address throttle parameters. Likelihood: 15%
- Connector or wiring problem – Corrosion or loose pins at the throttle body. Likelihood: 15%
- Intake vacuum leak – Deteriorated gasket or cracked hose. Likelihood: 5%
Symptoms You May Notice
- Check Engine Light on
- Rough or unstable idle
- Hesitation when pressing the gas
- Reduced power, especially noticeable with the 2.4L engine
- Cruise control issues
- ESC warnings
How Serious Is This Code?
P0121 is medium severity. Your 2021 Cherokee will remain drivable but with compromised throttle response. The 2.4L four-cylinder already has limited power, so any throttle issue is more noticeable. Address it soon—within 1-2 weeks.
Diagnostic Steps
- Scan for codes and review 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 corrosion and proper seating
- Inspect wiring from throttle body to PCM
- Check for vacuum leaks around the intake
Estimated Repair Costs
- Throttle body cleaning: $100–$200 (DIY: $10–$20)
- Throttle body replacement: $300–$550
- Wiring repair: $150–$300
- PCM reflash: $100–$150 at dealer
Can You DIY This Fix?
DIY feasibility is moderate. The Cherokee's engine bay provides decent access to the throttle body on both engine options. Clean with dedicated throttle body cleaner. After cleaning, disconnect the battery for 15-20 minutes, reconnect, start, and idle 10 minutes for the PCM to relearn.
Check your warranty—the 2021 Cherokee's basic warranty (3 years/36,000 miles) has likely expired. The 5-year/60,000-mile powertrain warranty extends through 2026. If your mileage qualifies, let the dealer handle the repair at no cost.