P0120 Code: Throttle/Pedal Position Sensor/Switch A Circuit Malfunction
Note: We do not currently have verified model-specific diagnostic data for the Jeep Cherokee. The symptoms and fixes listed below are the standard generic OBD2 guidelines for the P0120 code. Always consult a factory service manual before replacing parts.
What does this mean?
Code P0120 signifies an electrical fault within the 'A' circuit of the Throttle Position Sensor (TPS) or Pedal Position Sensor (PPS). The Powertrain Control Module (PCM) uses this sensor to precisely monitor the throttle blade's angle, which directly correlates to the driver's acceleration input. A malfunction in this circuit means the PCM is receiving an implausible signal, an intermittent signal, or no signal at all from sensor 'A', leading to incorrect fuel delivery and transmission shift strategies, and potentially affecting engine performance and drivability.
How serious is this code?
Driving with a P0120 code can be hazardous. The vehicle may experience erratic idle, sudden loss of power, hesitation during acceleration, or enter "limp home" mode, severely limiting speed and power. This unpredictable behavior can increase the risk of accidents, especially in traffic or at higher speeds. It is strongly recommended to diagnose and repair this issue promptly.
Diagnostic system: Sensor circuit and live data
On a Jeep Cherokee, the P0120 code should be diagnosed as part of the sensor circuit and live data group. Related codes and live data from this same system can change the repair priority, so avoid replacing parts from the code name alone.
Most Common Causes for Jeep Cherokee
- Faulty throttle position sensor (TPS)
- Damaged, chafed, or broken wiring harness
- Corroded or loose electrical connector
- Dirty or faulty throttle body
Symptoms to Watch For
- Check Engine Light is illuminated
- Poor acceleration or sluggish response
- Engine surging or fluctuating RPM
- Engine stalling or dying unexpectedly
- Erratic or fluctuating idle speed
- Vehicle enters reduced power / limp mode
Before replacing parts, check these first
- Inspect the connector for corrosion, broken locks, oil intrusion, or heat damage.
- Verify 5V reference, ground, and signal with a multimeter where applicable.
- Compare live sensor data to realistic engine temperature, pressure, airflow, or throttle values.
- Check for blown fuses, weak battery voltage, and damaged connectors before buying major parts.
Live data to compare
- 5V reference, ground, and signal voltage
- Sensor value compared with realistic engine conditions
- Connector wiggle-test result
How to Diagnose
Common Mistakes
Replacing the named sensor without testing power, ground, signal, and wiring continuity first. Always confirm the fault with freeze-frame data, live data, visual inspection, and circuit checks before spending money on parts.
Repair verification
After the repair, clear P0120, complete a drive cycle, and confirm the monitor runs without the code returning. Save the before/after scan report if the vehicle needs emissions inspection.
Frequently Asked Questions
Can I drive with the P0120 code?
If the check engine light is solid, you can usually drive to a safe location or mechanic. If the light is flashing, pull over immediately to prevent catastrophic engine or catalytic converter damage.
Will the P0120 code clear itself?
Once the underlying problem is fixed, the engine computer will run its self-checks. If it passes over several drive cycles, the light will turn off automatically. You can also clear it immediately using an OBD2 scanner.
Will this code fail an emissions test?
Yes. If the Check Engine Light is on due to the P0120 code, your Jeep will automatically fail an OBD2 plug-in emissions or smog test.
What should I check first for P0120?
Inspect the connector for corrosion, broken locks, oil intrusion, or heat damage. Verify 5V reference, ground, and signal with a multimeter where applicable. Compare live sensor data to realistic engine temperature, pressure, airflow, or throttle values.
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Repair Estimate
Fuse, connector, wiring, cleaning, or basic inspection
Major component replacement after live data and circuit tests confirm failure
Sensor replacement can be moderate cost, but wiring and connector repairs are common and cheaper.
DIY Difficulty
Can usually be performed at home with basic hand tools.