AutoCodes – Buick – P2120 Buick

P2120 Buick Code - Accelerator Pedal Position Sensor 1 Circuit

Quick Answer

The Accelerator Pedal Position (APP) sensor is made up of 2 sensors that are housed inside one assembly. Common causes include Faulty Accelerator Pedal Position Sensor, Accelerator Pedal Position Sensor harness is open or shorted, Accelerator Pedal Position Sensor circuit poor electrical connection. 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: P2120 Buick indicates Accelerator Pedal Position Sensor 1 Circuit.
Common causes: Common causes include Faulty Accelerator Pedal Position Sensor, Accelerator Pedal Position Sensor harness is open or shorted, Accelerator Pedal Position Sensor circuit poor electrical connection.
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.

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Code Popularity 4,898

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 14, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P2120 Buick Description

The Accelerator Pedal Position (APP) sensor is made up of 2 sensors that are housed inside one assembly. The Engine Control Module (ECM) supplies a separate 5-volt reference circuit and a low reference circuit for each of the sensors. The 5-volt reference for APP sensor 1 is supplied from the same source in the ECM as the 5-volt reference for the mass air flow (MAF) sensor and the fuel tank pressure (FTP) sensor. The 5-volt reference voltage for all of the sensors is supplied on separate ECM terminals, but the terminals are connected internally to a voltage supply. The APP sensor 1 sends a signal from the sensor to the ECM indicating the accelerator pedal position. The ECM actuates the throttle plates based on this information. If the ECM detects that the APP sensors are not within a predicted value from each other, DTC P2120 sets.

OBDII Code P2120 Buick - Accelerator Pedal Position Sensor 1 Circuit - AutoCodes.com — P2120 Buick Code - Accelerator Pedal Position Sensor 1 Circuit

What does this mean?

What are the Possible Causes of the DTC P2120 Buick?

Faulty Accelerator Pedal Position Sensor
Accelerator Pedal Position Sensor harness is open or shorted
Accelerator Pedal Position Sensor circuit poor electrical connection
Faulty Electric Throttle Control Actuator

How to Fix the DTC P2120 Buick?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P2120 Buick code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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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 P2120 Buick Code

What does the OBDII code P2120 mean on a Buick?

P2120 indicates a problem with the Accelerator Pedal Position (APP) Sensor 1 Circuit, meaning the sensor is sending incorrect or no signals to the engine control module (ECM).

What are the common symptoms of P2120 in a Buick?

Symptoms include reduced engine power, the Check Engine Light turning on, delayed acceleration, or the vehicle entering "limp mode."

What causes the P2120 code to appear?

Common causes include a faulty accelerator pedal position sensor, damaged wiring or connectors, or issues with the ECM.

Can I drive my Buick with the P2120 code?

It’s not recommended to drive with this code as it may cause unsafe driving conditions due to limited acceleration or the vehicle entering limp mode.

How do I diagnose the P2120 code on my Buick?

Start by checking the accelerator pedal position sensor and inspecting the wiring and connectors for damage or loose connections. A diagnostic scan tool can also help monitor sensor data.

How is the P2120 code fixed?

Repairs may include replacing the APP sensor, repairing or replacing damaged wiring or connectors, or in rare cases, replacing the ECM.

How much does it cost to repair the P2120 code on a Buick?

Repair costs can vary, but replacing the APP sensor typically ranges from $150 to $300, including parts and labor.

Can a dirty throttle body cause the P2120 code?

While less common, a dirty or malfunctioning throttle body could potentially contribute to issues with the APP sensor circuit.

Will disconnecting the battery clear the P2120 code?

Disconnecting the battery may temporarily clear the code but won’t resolve the underlying problem. The issue will likely return until proper repairs are made.

How do I prevent the P2120 code from recurring?

Regular maintenance, including inspecting wiring and ensuring the APP sensor remains clean and functional, can help prevent the code from recurring.