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Engine-Codes – Toyota – P0122 2009 Toyota Prius

P0122 2009 Toyota Prius Code - Throttle Position Sensor/Switch 'A' Circuit Low Input

Quick Answer

The P0122 code for a 2009 Toyota Prius indicates a Throttle Position Sensor/Switch 'A' Circuit Low Input. Common causes include Malfunctioning throttle position sensor (TPS), Damaged wiring or connectors in the TPS circuit, Corrosion or contamination affecting TPS operation. 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
P0122 2009 Toyota Prius indicates Throttle Position Sensor/Switch 'A' Circuit Low Input.
Common causes
Common causes include Malfunctioning throttle position sensor (TPS), Damaged wiring or connectors in the TPS circuit, Corrosion or contamination affecting TPS operation.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 12, 2024
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Code P0122 2009 Toyota Prius Description

The P0122 code for a 2009 Toyota Prius indicates a Throttle Position Sensor/Switch 'A' Circuit Low Input. The throttle position sensor (TPS) is a crucial component of the electronic throttle control system that communicates the position of the throttle to the engine control module (ECM). When the TPS 'A' circuit reports a low input signal, it means that the voltage signal being sent by the sensor is below the expected range, leading to potential issues with engine performance and drivability.

OBDII Code P0122 2009 Toyota Prius - Throttle Position Sensor/Switch 'A' Circuit Low Input
P0122 2009 Toyota Prius Code - Throttle Position Sensor/Switch 'A' Circuit Low Input

Common Causes of P0122 2009 Toyota Prius

  1. Malfunctioning throttle position sensor (TPS)
  2. Damaged wiring or connectors in the TPS circuit
  3. Corrosion or contamination affecting TPS operation
  4. Faulty ECM or other related control modules
  5. Issues with the throttle body assembly

Symptoms of P0122 2009 Toyota Prius

  1. Reduced engine power and response
  2. Engine stalling or rough idling
  3. Poor acceleration and throttle response
  4. Check Engine Light illuminated on the dashboard
  5. Potential for decreased fuel efficiency

How to Fix P0122 2009 Toyota Prius

  1. Begin by diagnosing the root cause of the issue using a diagnostic scanner to confirm the P0122 code.
  2. Inspect the throttle position sensor, wiring, and connectors for any signs of damage or corrosion.
  3. If the TPS is faulty, replace it with a new OEM part and recalibrate it as per manufacturer guidelines.
  4. Clear the error code from the ECM and perform a test drive to ensure the issue has been resolved.
  5. If the problem persists, further diagnostics may be required to identify any other underlying issues with the throttle control system.

Cost to Fix P0122 2009 Toyota Prius

The typical repair costs for addressing a P0122 code on a 2009 Toyota Prius can range from $150 to $300, depending on the specific parts needed and labor involved. It's important to note that prices can vary significantly based on the location, dealership rates, and the extent of the repairs required. Additionally, diagnosis time and labor rates at auto repair shops can also impact the final cost. It's advisable to obtain quotes from multiple sources and consider the expertise of the technicians performing the repair.

What does this mean?

Tech Notes for P0122 2009 Toyota Prius

Before replacing any parts, try cleaning the throttle body and reset the light. If the codes come back, then it will necessary to replaced the throttle position sensor (TPS).

When is the Code Detected?

An excessively low voltage from the Throttle Position Sensor (TPS) is sent to Engine Control Module (ECM).

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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 P0122 2009 Toyota Prius Code

1. What are the common symptoms of OBDII code P0122 on a 2009 Toyota Prius?

The common symptoms of code P0122 in a 2009 Toyota Prius include reduced engine power, hesitation or stalling when accelerating, and the vehicle going into limp mode.

2. What causes the Throttle Position Sensor/Switch 'A' Circuit Low Input code (P0122) on a 2009 Toyota Prius?

The P0122 code on a 2009 Toyota Prius is typically caused by a faulty throttle position sensor, damaged wiring or connectors in the throttle position sensor circuit, or issues with the engine control module.

3. How can I diagnose the Throttle Position Sensor/Switch 'A' Circuit Low Input code (P0122) on my 2009 Toyota Prius?

Diagnosing the P0122 code involves using a scan tool to read the code, checking the throttle position sensor's voltage output, inspecting the wiring and connectors for damage, and testing the throttle position sensor's resistance.

4. Can I drive my 2009 Toyota Prius with OBDII code P0122?

It is not recommended to drive your 2009 Toyota Prius with the P0122 code present, as it can lead to further damage to the engine or catalytic converter. It's best to address the issue promptly.

5. How do I repair the Throttle Position Sensor/Switch 'A' Circuit Low Input code (P0122) on a 2009 Toyota Prius?

To repair the P0122 code, you may need to replace the throttle position sensor, repair any damaged wiring or connectors in the circuit, or reprogram the engine control module. It's recommended to consult a professional mechanic for proper diagnosis and repair.

6. Is it possible to reset the OBDII code P0122 on a 2009 Toyota Prius by disconnecting the battery?

Disconnecting the battery may temporarily clear the P0122 code, but it is not a permanent solution. The underlying issue causing the code must be diagnosed and repaired to prevent it from reoccurring.

7. How much does it cost to fix OBDII code P0122 on a 2009 Toyota Prius?

The cost to fix the P0122 code on a 2009 Toyota Prius can vary depending on the cause of the issue, parts needed for repair, and labor costs. It's advisable to get a professional diagnosis and estimate from a trusted mechanic.

8. Can a dirty throttle body cause OBDII code P0122 on a 2009 Toyota Prius?

While a dirty throttle body can cause related issues, such as poor acceleration or rough idling, it is not a common cause of the specific P0122 code. It's best to focus on inspecting the throttle position sensor and its circuit for this code.

9. Will replacing the throttle position sensor fix OBDII code P0122 on a 2009 Toyota Prius?

Replacing the throttle position sensor may resolve the P0122 code if the sensor is indeed faulty. However, it's essential to properly diagnose the issue to ensure that the sensor replacement will address the root cause of the code.

10. Can a DIY enthusiast repair OBDII code P0122 on a 2009 Toyota Prius?

While some DIY enthusiasts may be able to diagnose and repair the P0122 code on a 2009 Toyota Prius, it is recommended to have the issue addressed by a professional mechanic due to the complexity of the throttle position sensor circuit and engine control system.

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