AutoCodesScion – P2128 Scion

P2128 Scion Code - Throttle Pedal Position Sensor/Switch 'E' Circuit Input High

Quick Answer

The Accelerator Pedal Position (APP) sensor is built into the accelerator pedal sensor assembly and has 2 sensor circuits: VPA (main) and VPA2 (sub). Common causes include Faulty Accelerator Pedal Position (APP) 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
P2128 Scion indicates Throttle Pedal Position Sensor/Switch 'E' Circuit Input High.
Common causes
Common causes include Faulty Accelerator Pedal Position (APP) 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 3,995
How popular is this code, among other codes? Low
Table of contents Created and updated by William Orellana on Sep 17, 2022
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Code P2128 Scion Description

The Accelerator Pedal Position (APP) sensor is built into the accelerator pedal sensor assembly and has 2 sensor circuits: VPA (main) and VPA2 (sub). This sensor is a non-contact type sensor and uses Hall-effect elements in order to yield accurate signals even in extreme driving conditions, such as at high speeds as well as very low speeds. The voltage, which is applied to terminals VPA and VPA2 of the Engine Control Module (ECM), varies between 0.5 V and 4.75 V in proportion to the operating angle of the accelerator pedal (throttle valve). A signal from VPA indicates the actual accelerator pedal opening angle (throttle valve opening angle) and is used for engine control. A signal from VPA2 conveys the status of the VPA circuit and is used to check the accelerator pedal position sensor itself.
The ECM monitors the actual accelerator pedal opening angle (throttle valve opening angle) through the signals from VPA and VPA2 and controls the throttle actuator according to these signals.
When either the output voltage of VPA or VPA2 deviates from the standard range, or the difference between the output voltages of the 2 sensor circuits is more than the threshold, the ECM determines that there is a malfunction in the accelerator pedal position sensor. The ECM then illuminates the MIL and stores a Diagnostic Trouble Code (DTC).
OBDII Code P2128 Scion - Throttle Pedal Position Sensor/Switch 'E' Circuit Input High - AutoCodes.com
P2128 Scion Code - Throttle Pedal Position Sensor/Switch 'E' Circuit Input High

What are the Possible Causes of the DTC P2128 Scion?

  • Faulty Accelerator Pedal Position (APP) Sensor
  • Accelerator Pedal Position Sensor harness is open or shorted
  • Accelerator Pedal Position Sensor circuit poor electrical connection
  • Faulty Engine Control Module (ECM)

How to Fix the DTC P2128 Scion?

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 P2128 Scion 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 P2128 Scion Code

What does the OBD-II code P2128 mean for a Scion?

Code P2128 indicates that the throttle pedal position sensor/switch 'E' circuit is reporting an input voltage that is higher than expected.

What are the symptoms of code P2128 on a Scion?

Common symptoms include reduced engine performance, hesitation during acceleration, difficulty starting the vehicle, and the check engine light turning on.

What causes the P2128 code on a Scion?

Possible causes include a faulty throttle pedal position sensor, damaged wiring or connectors in the circuit, or issues with the ECM (engine control module).

Can I drive my Scion with code P2128 active?

While the car may still be drivable, reduced throttle response and performance could lead to unsafe driving conditions. It’s best to address the issue promptly.

How do you diagnose the P2128 code on a Scion?

A mechanic typically uses a scan tool to check the code, inspects the throttle pedal position sensor, and examines the wiring and connectors for damage or corrosion.

How do you fix code P2128 on a Scion?

Common fixes include replacing the throttle pedal position sensor, repairing or replacing damaged wiring, and clearing the code with a diagnostic tool.

What tools are needed to repair code P2128?

Basic tools include a multimeter for testing voltage, a scan tool for code diagnostics, and replacement parts like the throttle pedal position sensor if necessary.

Could a dirty throttle body cause the P2128 code?

No, a dirty throttle body typically causes other codes related to airflow rather than the throttle pedal position sensor circuit.

How much does it cost to fix the P2128 code on a Scion?

Repair costs vary but typically range from $100 to $300 for parts and labor, depending on whether the sensor or wiring needs replacement.

Will clearing the P2128 code fix the problem permanently?

Clearing the code does not resolve the underlying issue; the root cause must be diagnosed and repaired to prevent the code from returning.

Discuss the causes and fixes for P2128 Scion OBDII Code

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