Engine-CodesInfiniti – P0138 2003 Infiniti G35

P0138 2003 Infiniti G35 Code - HO2S12 Circuit High Voltage

Quick Answer

The P0138 diagnostic trouble code (DTC) for a 2003 Infiniti G35 indicates an issue with the HO2S12 (Heated Oxygen Sensor 1 Bank 1 Sensor 2) circuit registering high voltage. Common causes include Faulty HO2S12 sensor, Wiring issues in the sensor circuit, Vacuum leaks. 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 2003 Infiniti G35 indicates HO2S12 Circuit High Voltage.
Common causes
Common causes include Faulty HO2S12 sensor, Wiring issues in the sensor circuit, Vacuum leaks.
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 17, 2024
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Code P0138 2003 Infiniti G35 Description

The P0138 diagnostic trouble code (DTC) for a 2003 Infiniti G35 indicates an issue with the HO2S12 (Heated Oxygen Sensor 1 Bank 1 Sensor 2) circuit registering high voltage. This sensor is responsible for monitoring the oxygen content in the exhaust gases and providing feedback to the engine control module (ECM) to adjust the air-fuel mixture for optimal combustion. When the voltage from the sensor is consistently higher than the specified range, it can lead to various performance issues in the vehicle.

OBDII Code P0138 2003 Infiniti G35 - HO2S12 Circuit High Voltage
P0138 2003 Infiniti G35 Code - HO2S12 Circuit High Voltage

Common Causes of P0138 2003 Infiniti G35

  1. Faulty HO2S12 sensor
  2. Wiring issues in the sensor circuit
  3. Vacuum leaks
  4. Exhaust system leaks
  5. Malfunctioning ECM

Symptoms of P0138 2003 Infiniti G35

  1. Decreased fuel efficiency
  2. Rough idling or stalling
  3. Hesitation or lack of power during acceleration
  4. Illuminated check engine light
  5. Failed emissions test

How to Fix P0138 2003 Infiniti G35

  1. Use an OBD-II scanner to confirm the P0138 code and diagnose the specific cause of the high voltage reading.
  2. Inspect the wiring and connections in the HO2S12 circuit for any damage or corrosion.
  3. Test the HO2S12 sensor using a multimeter to check for proper voltage output.
  4. Replace the HO2S12 sensor if it is found to be faulty, ensuring proper installation and connection.
  5. Clear the DTC and test drive the vehicle to verify that the issue has been resolved.

Cost to Fix P0138 2003 Infiniti G35

The typical repair costs for addressing a P0138 code on a 2003 Infiniti G35 can range from $150 to $400, including parts and labor. However, it's important to note that specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. Auto repair shops commonly charge between $80 and $150 per hour for labor, with rates potentially higher in metropolitan areas or at dealerships, and lower at independent shops. It's recommended to inquire about local rates for a more accurate estimate.

Tech Notes for P0138 2003 Infiniti G35

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 2003 Infiniti G35 Code

1. What does OBDII code P0138 for a 2003 Infiniti G35 mean?

Code P0138 indicates a high voltage condition in the HO2S12 (Heated Oxygen Sensor Bank 1 Sensor 2) circuit of the vehicle.

2. What are the common symptoms of OBDII code P0138 in a 2003 Infiniti G35?

Common symptoms 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 2003 Infiniti G35?

Potential causes include a faulty HO2S12 sensor, wiring issues in the sensor circuit, exhaust leaks, or problems with the engine's fuel system.

4. How can I diagnose the OBDII code P0138 in my 2003 Infiniti G35?

Diagnosis typically involves using an OBDII scanner to retrieve the code, inspecting the HO2S12 sensor and its wiring for damage, and checking for exhaust leaks.

5. Can I still drive my 2003 Infiniti G35 with OBDII code P0138?

It is not recommended to continue driving with code P0138 as it can lead to poor engine performance and potential damage in the long run. It's best to address the issue promptly.

6. How can I repair OBDII code P0138 in my 2003 Infiniti G35?

Repair options may include replacing the HO2S12 sensor, repairing damaged wiring, fixing exhaust leaks, or addressing any fuel system issues that may be contributing to the code.

7. Can I reset the OBDII code P0138 in my 2003 Infiniti G35 without fixing the underlying issue?

While you can clear the code using an OBDII scanner, the check engine light is likely to reappear if the root cause of the code is not addressed.

8. Is it possible for a dirty or contaminated sensor to trigger OBDII code P0138 in a 2003 Infiniti G35?

Yes, a dirty or contaminated HO2S12 sensor can sometimes cause erroneous readings and lead to a high voltage condition, triggering code P0138.

9. How much does it typically cost to repair OBDII code P0138 in a 2003 Infiniti G35?

The cost of repair can vary depending on the specific issue causing the code, but it may range from around $100 to $300 or more, including parts and labor.

10. How often should I replace the oxygen sensors in my 2003 Infiniti G35 to prevent OBDII code P0138 from recurring?

Oxygen sensors typically have a lifespan of around 60,000 to 90,000 miles. Regularly inspecting and replacing sensors as needed can help prevent issues like code P0138 from reoccurring.

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