P0121 on Jeep: How to Diagnose & Fix
Throttle/Pedal Position Sensor Circuit Range/Performance
1 Jeep model · 1 documented issue · $50-$220 repair
P0121 on Jeep by model: symptoms, diagnosis and fix
The throttle-body-mounted TPS wears and produces an erratic voltage signal, causing high/hunting idle, stalling at stops, hesitation or bucking on acceleration, and — on automatics — erratic or harsh shifting. It is a very common TJ driveability complaint and often turns on the check-engine light.
Common Symptoms
- High or hunting idle
- Stalling when coming to a stop
- Hesitation/bucking on acceleration
- Erratic or harsh automatic shifting
- Check-engine light
How to Fix
Confirm with a scan tool (P0121/P0122/P0123) and swap in a quality TPS — Mopar 04874371AC (superseded by 68433984AA) for 1997-2001 TJs, or 05019411AD for 2002-2006 TJs. Owners strongly recommend Mopar, Standard Ignition, or NGK over cheap economy sensors, which frequently fail again. Verify closed-throttle voltage and idle relearn after install.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Omix 17224.04 throttle-position sensorOEMOmix 17224.04
Replace a circuit-tested TPS on the early throttle-body branch Fitment/availability: 1997-2001 Wrangler TJ 2.5L or 4.0L; verify connector and throttle-body/tang geometry before ordering.
- Genuine Mopar 68404428AA throttle-position sensorOEMMopar 68404428AA
Replace a circuit-tested TPS on the later throttle-body branch Fitment/availability: 2002-2006 Wrangler TJ/Unlimited with 2.4L or 4.0L as cataloged; verify VIN and connector.
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Sources for this issue (2)
P0121 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0121 mean on a Jeep?
P0121 stands for "Throttle/Pedal Position Sensor Circuit Range/Performance." This code means the throttle position (or accelerator pedal position) sensor's signal does not match what the computer expects compared with other inputs like airflow, RPM, and the second throttle/pedal sensor. The sensor tells the computer how far the throttle or pedal is open; when its range or performance is off, the computer can't trust how much power you're requesting. You may notice hesitation, surging, poor acceleration, rough idle, or the vehicle dropping into a reduced-power 'limp' mode. It indicates an out-of-range or implausible signal rather than a complete loss of signal. On Jeep it is documented across 1 model: Wrangler.
What are the most common causes of P0121?
The most common causes of P0121 are: Worn or failing throttle position sensor, Dirty or carboned-up throttle body affecting plate position, Damaged, frayed, or shorted sensor wiring, Corroded or loose sensor connector, Poor sensor ground or reference voltage, Faulty throttle body / electronic throttle actuator, Mismatch between the two throttle or pedal sensor signals. The specific cause varies by vehicle.
How much does it cost to fix P0121 on a Jeep?
Published repair estimates on Jeep range from $50 to $220 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.