Engine-CodesToyota – P0138 2009 Toyota Prius

P0138 2009 Toyota Prius Code - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2

Quick Answer

The P0138 diagnostic trouble code (DTC) on a 2009 Toyota Prius indicates a high voltage condition in the Oxygen Sensor Circuit for Bank 1 Sensor 2. Common causes include Faulty oxygen sensor, Damaged or corroded sensor wiring, Exhaust leaks near the sensor. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means
P0138 2009 Toyota Prius indicates Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2.
Common causes
Common causes include Faulty oxygen sensor, Damaged or corroded sensor wiring, Exhaust leaks near the sensor.
Severity
Moderate - service should be scheduled soon.
Can I drive?
The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
Table of contents Created and updated by William Orellana on Sep 10, 2024
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Code P0138 2009 Toyota Prius Description

The P0138 diagnostic trouble code (DTC) on a 2009 Toyota Prius indicates a high voltage condition in the Oxygen Sensor Circuit for Bank 1 Sensor 2. This sensor is located downstream of the catalytic converter and is responsible for monitoring the oxygen levels in the exhaust gases. The engine control module (ECM) uses this data to adjust the air-fuel mixture for optimal combustion and reduce harmful emissions.

OBDII Code P0138 2009 Toyota Prius - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2
P0138 2009 Toyota Prius Code - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2

Common Causes of P0138 2009 Toyota Prius

  1. Faulty oxygen sensor
  2. Damaged or corroded sensor wiring
  3. Exhaust leaks near the sensor
  4. Issues with the ECM
  5. Engine running too rich

Symptoms of P0138 2009 Toyota Prius

  1. Decreased fuel efficiency
  2. Rough idling or stalling
  3. Engine misfires
  4. Illumination of the check engine light
  5. Increased emissions during emissions testing

How to Fix P0138 2009 Toyota Prius

  1. Begin by identifying the location of Bank 1 Sensor 2, downstream of the catalytic converter.
  2. Inspect the sensor wiring for any signs of damage or corrosion. Replace any damaged wiring.
  3. Test the oxygen sensor using a multimeter to check its voltage output. Replace the sensor if it is faulty.
  4. Clear the DTC using an OBD-II scanner and monitor the sensor's performance to ensure the issue is resolved.
  5. If the problem persists, further diagnosis may be required to identify any underlying issues with the ECM or engine components.

Cost to Fix P0138 2009 Toyota Prius

The cost of repairing a P0138 code on a 2009 Toyota Prius can vary depending on the root cause of the issue. On average, replacing an oxygen sensor can cost between $200 and $300, including parts and labor. However, if additional repairs or diagnostics are needed, the cost may increase. It is advisable to consult with a qualified mechanic or dealership for an accurate estimate based on the specific circumstances of your vehicle. Keep in mind that labor rates can vary, so it's essential to inquire about rates in your area before proceeding with the repair.

When is the Code Detected?

The P0138 code is set when the Engine Control Module (ECM) detects that the rear O2 sensor signal voltage remains excessively high for an extended period of time.

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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 P0138 2009 Toyota Prius Code

1. What does the OBDII code P0138 for a 2009 Toyota Prius indicate?

The code P0138 in a 2009 Toyota Prius indicates an Oxygen Sensor Circuit High Voltage condition in Bank 1 Sensor 2.

2. What are the common symptoms of a P0138 code in a 2009 Toyota Prius?

Common symptoms of a P0138 code in a 2009 Toyota Prius include poor fuel efficiency, rough idling, and potential engine misfires.

3. What are the possible causes of the P0138 code in a 2009 Toyota Prius?

Possible causes of a P0138 code in a 2009 Toyota Prius include a faulty oxygen sensor, wiring issues, exhaust leaks, or a malfunctioning catalytic converter.

4. How can I diagnose the P0138 code in a 2009 Toyota Prius?

To diagnose a P0138 code in a 2009 Toyota Prius, you can use an OBDII scanner to read the code, visually inspect the oxygen sensor and its wiring, and check for any exhaust leaks.

5. How can I repair a P0138 code in a 2009 Toyota Prius?

Repairing a P0138 code in a 2009 Toyota Prius may involve replacing the Bank 1 Sensor 2 oxygen sensor, repairing any damaged wiring, fixing exhaust leaks, or replacing the catalytic converter if necessary.

6. Can I drive my 2009 Toyota Prius with a P0138 code?

It is not recommended to drive your 2009 Toyota Prius with a P0138 code for an extended period as it can lead to decreased fuel efficiency and potential damage to the engine and catalytic converter.

7. How much does it cost to fix a P0138 code in a 2009 Toyota Prius?

The cost to fix a P0138 code in a 2009 Toyota Prius can vary depending on the exact cause of the issue, but it may range from $100 to $500 or more for parts and labor.

8. How often does the oxygen sensor need to be replaced in a 2009 Toyota Prius?

The oxygen sensor in a 2009 Toyota Prius typically needs to be replaced every 60,000 to 90,000 miles, but it can vary based on driving conditions and maintenance practices.

9. Can a P0138 code in a 2009 Toyota Prius cause the Check Engine light to come on?

Yes, a P0138 code in a 2009 Toyota Prius can trigger the Check Engine light to illuminate on the dashboard as it indicates a problem with the oxygen sensor circuit.

10. Is it possible to reset the P0138 code in a 2009 Toyota Prius without fixing the underlying issue?

While you can clear the code temporarily, it is not recommended to reset the P0138 code in a 2009 Toyota Prius without addressing the root cause, as the issue may persist and lead to further problems.

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