Engine-CodesGMC – P1120 GMC

P1120 GMC Code - Throttle Position Sensor 1 Circuit

Quick Answer

The P1120 GMC diagnostic trouble code indicates an issue with the Throttle Position Sensor 1 Circuit in the vehicle. Common causes include Faulty Throttle Position Sensor, Damaged or corroded wiring connected to the sensor, Loose or poor connection to the sensor. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P1120 GMC indicates Throttle Position Sensor 1 Circuit.
Common causes
Common causes include Faulty Throttle Position Sensor, Damaged or corroded wiring connected to the sensor, Loose or poor connection to the sensor.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Table of contents Created and updated by William Orellana on Sep 10, 2024
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Code P1120 GMC Description

The P1120 GMC diagnostic trouble code indicates an issue with the Throttle Position Sensor 1 Circuit in the vehicle. The Throttle Position Sensor (TPS) is a crucial component of the engine management system, as it helps to regulate the amount of air entering the engine. This information is used by the engine control module (ECM) to adjust the air-fuel mixture and optimize engine performance.

OBDII Code P1120 GMC - Throttle Position Sensor 1 Circuit
P1120 GMC Code - Throttle Position Sensor 1 Circuit

Common Causes of P1120 GMC

  1. Faulty Throttle Position Sensor
  2. Damaged or corroded wiring connected to the sensor
  3. Loose or poor connection to the sensor
  4. ECM software issue
  5. Mechanical issue with the throttle body

Symptoms of P1120 GMC

  1. Engine hesitation or surging
  2. Reduced fuel efficiency
  3. Difficulty starting the engine
  4. Illuminated Check Engine Light
  5. Reduced engine power

How to Fix P1120 GMC

  1. Begin by connecting a diagnostic scanner to the vehicle's OBD-II port to retrieve the specific trouble code.
  2. Inspect the wiring and connections related to the Throttle Position Sensor for any damage or corrosion. Repair or replace as needed.
  3. Test the Throttle Position Sensor using a multimeter to ensure it is functioning correctly. Replace the sensor if it is faulty.
  4. Clear the trouble code from the ECM's memory using the diagnostic scanner and test drive the vehicle to ensure the issue has been resolved.
  5. If the problem persists, consult a professional mechanic for further diagnosis and potential ECM reprogramming.

Cost to Fix P1120 GMC

The typical repair costs for addressing a P1120 GMC code can vary depending on the specific cause of the issue. In general, the cost of replacing a Throttle Position Sensor can range from $50 to $200, while labor costs can add an additional $80 to $150 per hour. Other potential costs may include diagnostic fees, wiring repairs, or ECM reprogramming. It is advisable to consult with a local auto repair shop for a more accurate estimate based on the vehicle make and model, as well as the extent of the repairs needed.

When is the Code Detected?

When the Powertrain Control Module (PCM) senses a signal voltage higher than the normal operating range of the sensor, the P1120 will set.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1120 GMC Code

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