Engine-CodesNissan – P0138 2002 Nissan Sentra

P0138 2002 Nissan Sentra Code - HO2S12 Circuit High Voltage

Quick Answer

The OBD-II code P0138 in a 2002 Nissan Sentra specifically refers to the Oxygen Sensor (HO2S12) Circuit High Voltage. Common causes include Faulty oxygen sensor (HO2S12), Wiring issues or shorts 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 2002 Nissan Sentra indicates HO2S12 Circuit High Voltage.
Common causes
Common causes include Faulty oxygen sensor (HO2S12), Wiring issues or shorts 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.
Table of contents Created and updated by William Orellana on Sep 12, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code P0138 2002 Nissan Sentra Description

The OBD-II code P0138 in a 2002 Nissan Sentra specifically refers to the Oxygen Sensor (HO2S12) Circuit High Voltage. This code indicates that the oxygen sensor located on the downstream side of the catalytic converter is sending a high voltage signal to the Engine Control Module (ECM). The oxygen sensor is responsible for measuring the oxygen content in the exhaust gases and providing feedback to the ECM to adjust the air-fuel mixture for optimal combustion.

OBDII Code P0138 2002 Nissan Sentra - HO2S12 Circuit High Voltage
P0138 2002 Nissan Sentra Code - HO2S12 Circuit High Voltage

Common Causes of P0138 2002 Nissan Sentra

  1. Faulty oxygen sensor (HO2S12)
  2. Wiring issues or shorts in the oxygen sensor circuit
  3. Exhaust leaks near the sensor
  4. Faulty ECM
  5. Engine misfires

Symptoms of P0138 2002 Nissan Sentra

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

How to Fix P0138 2002 Nissan Sentra

  1. Use an OBD-II scanner to confirm the P0138 code and check for any additional codes.
  2. Inspect the oxygen sensor wiring and connector for any damage or corrosion. Repair or replace as needed.
  3. Perform a visual inspection of the exhaust system for leaks near the sensor. Repair any leaks found.
  4. Test the HO2S12 sensor using a multimeter to ensure it is functioning properly. Replace the sensor if necessary.
  5. Clear the fault codes and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0138 2002 Nissan Sentra

The cost of repairing a P0138 code in a 2002 Nissan Sentra can vary depending on the root cause of the issue. On average, the cost of replacing an oxygen sensor can range from $100 to $300, including parts and labor. Additional costs may apply if wiring repairs or ECM replacement are necessary. It is recommended to consult with a trusted mechanic or auto repair shop for a more accurate estimate based on the specific circumstances of your vehicle. Keep in mind that labor rates and part prices can vary significantly based on location and the repair facility.

Tech Notes for P0138 2002 Nissan Sentra

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.

Need more information about the P0138 2002 Nissan Sentra code?

Need more information on how to fix the P0138 2002 Nissan Sentra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0138 2002 Nissan Sentra code diagnosed by a professional: Find a repair shop in your area

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 2002 Nissan Sentra Code

1. What are common symptoms of OBDII code P0138 on a 2002 Nissan Sentra?

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

2. What does the HO2S12 Circuit High Voltage code P0138 mean for a 2002 Nissan Sentra?

- This code indicates that the oxygen sensor (O2 sensor) located in bank 1 sensor 2 is detecting a high voltage condition.

3. What are possible causes of OBDII code P0138 on a 2002 Nissan Sentra?

- Possible causes include a faulty oxygen sensor, wiring issues in the sensor circuit, a vacuum leak, exhaust system leaks, or engine misfires.

4. How can I diagnose the HO2S12 Circuit High Voltage code P0138 on my 2002 Nissan Sentra?

- Diagnosis typically involves using an OBDII scanner to read the code, checking the oxygen sensor's voltage readings, inspecting the sensor wiring, and looking for any exhaust or vacuum leaks.

5. Can I continue driving my 2002 Nissan Sentra with OBDII code P0138?

- It is not advisable to drive for an extended period with this code as it can lead to poor engine performance and potential damage to the catalytic converter.

6. How do I repair OBDII code P0138 on my 2002 Nissan Sentra?

- Repair options may include replacing the oxygen sensor, repairing any damaged wiring, fixing vacuum or exhaust leaks, and ensuring proper engine operation.

7. Will resetting the Check Engine Light fix the P0138 code on my 2002 Nissan Sentra?

- Resetting the light may temporarily turn it off, but it will not fix the underlying issue causing the code. Proper diagnosis and repair are recommended.

8. How much does it cost to repair OBDII code P0138 on a 2002 Nissan Sentra?

- The cost of repair can vary depending on the exact cause of the code, but it may involve parts and labor expenses ranging from $100 to $500 or more.

9. Can a DIY enthusiast fix OBDII code P0138 on a 2002 Nissan Sentra?

- Depending on the individual's skill level and access to tools, some DIY enthusiasts may be able to diagnose and repair this code, especially if it involves simple tasks like sensor replacement.

10. How often does the HO2S12 Circuit High Voltage code P0138 occur in 2002 Nissan Sentras?

- While the occurrence rate may vary, this code is relatively common in older vehicles like the 2002 Nissan Sentra due to sensor wear and wiring degradation over time.

Discuss the causes and fixes for P0138 2002 Nissan Sentra OBDII Code

Code P0138 2002 Nissan Sentra comments

No comments found for this page.