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Engine-Codes – Toyota – P0138 2001 Toyota Highlander

P0138 2001 Toyota Highlander Code - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2

Quick Answer

The diagnostic trouble code P0138 for a 2001 Toyota Highlander indicates an issue with the Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2. Common causes include Faulty oxygen sensor, Wiring or connector issues in the oxygen sensor circuit, 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 2001 Toyota Highlander indicates Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2.
Common causes
Common causes include Faulty oxygen sensor, Wiring or connector issues in the oxygen sensor circuit, 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.
What is this?
Table of contents Created and updated by William Orellana on Sep 13, 2024
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Code P0138 2001 Toyota Highlander Description

The diagnostic trouble code P0138 for a 2001 Toyota Highlander indicates an issue with the Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2. This code specifically refers to the oxygen sensor located downstream or after the catalytic converter in the exhaust system. The oxygen sensor is responsible for measuring the amount of oxygen in the exhaust gases and sending this information to the engine control module (ECM) to adjust the air-fuel mixture for optimal combustion.

OBDII Code P0138 2001 Toyota Highlander - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2
P0138 2001 Toyota Highlander Code - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2

Common Causes of P0138 2001 Toyota Highlander

  1. Faulty oxygen sensor
  2. Wiring or connector issues in the oxygen sensor circuit
  3. Exhaust leaks near the sensor
  4. Engine running rich due to a separate issue
  5. ECM software or hardware problems

Symptoms of P0138 2001 Toyota Highlander

  1. Decreased fuel efficiency
  2. Rough idling or stalling
  3. Check Engine Light illuminated
  4. Increased emissions
  5. Engine misfires

How to Fix P0138 2001 Toyota Highlander

  1. Begin by diagnosing the specific cause of the high voltage reading, such as testing the oxygen sensor and inspecting the wiring for any damage.
  2. Replace the oxygen sensor if it is found to be faulty or not functioning correctly.
  3. Repair any damaged wiring or connectors in the oxygen sensor circuit.
  4. Check for and repair any exhaust leaks near the sensor that could be affecting its readings.
  5. Clear the diagnostic trouble codes and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0138 2001 Toyota Highlander

The cost of repairing a P0138 code on a 2001 Toyota Highlander can vary depending on the specific cause of the issue. In general, the cost of replacing an oxygen sensor can range from $100 to $300 for the part alone. Labor costs at an auto repair shop can add an additional $100 to $200, bringing the total repair cost to approximately $200 to $500. It's important to note that these are rough estimates, and actual costs may vary based on the location, labor rates, and any additional parts or repairs needed. It's recommended to consult with a qualified mechanic or auto repair shop for a more accurate cost estimate.

What does this mean?

Tech Notes for P0138 2001 Toyota Highlander

Replacing the Rear Heated Oxygen Sensor Bank 1 usually takes care of the problem.

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 2001 Toyota Highlander Code

1. What is OBDII code P0138 for a 2001 Toyota Highlander?

- OBDII code P0138 indicates an issue with the Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2 in a 2001 Toyota Highlander.

2. What are the common symptoms of OBDII code P0138 in a 2001 Toyota Highlander?

- Common symptoms of P0138 may include poor fuel economy, rough idling, engine misfires, and the illumination of the Check Engine Light.

3. What are the possible causes of OBDII code P0138 in a 2001 Toyota Highlander?

- The common causes of P0138 include a faulty oxygen sensor, damaged wiring or connectors in the sensor circuit, exhaust leaks, or issues with the engine's air-fuel ratio.

4. How can I diagnose OBDII code P0138 in my 2001 Toyota Highlander?

- To diagnose P0138, you can use an OBDII scanner to retrieve the code, visually inspect the sensor and its wiring, check for exhaust leaks, and perform voltage tests on the sensor.

5. Can I drive my 2001 Toyota Highlander with OBDII code P0138?

- It is generally not recommended to drive your vehicle with an unresolved P0138 code, as it can lead to decreased fuel efficiency and potential damage to the catalytic converter.

6. How do I repair OBDII code P0138 in my 2001 Toyota Highlander?

- Repairing P0138 may involve replacing the oxygen sensor, repairing damaged wiring or connectors, fixing exhaust leaks, or addressing any underlying issues affecting the air-fuel ratio.

7. Can a DIY enthusiast fix OBDII code P0138 in a 2001 Toyota Highlander?

- Depending on your experience and tools, a DIY enthusiast may be able to repair P0138 by replacing the oxygen sensor or addressing simple wiring issues. However, more complex repairs may require professional assistance.

8. How much does it cost to repair OBDII code P0138 in a 2001 Toyota Highlander?

- The cost of repairing P0138 can vary based on the specific issue causing the code. Replacing an oxygen sensor may cost between $100 to $300, while addressing wiring or exhaust leaks could increase the overall repair cost.

9. How often should the oxygen sensor be replaced in a 2001 Toyota Highlander?

- The oxygen sensor typically needs replacement every 60,000 to 90,000 miles, but this can vary based on driving conditions and vehicle usage. Regular maintenance can help prevent issues like P0138.

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