Engine-CodesInfiniti – P0138 2004 Infiniti G35

P0138 2004 Infiniti G35 Code - HO2S12 Circuit High Voltage

Quick Answer

The P0138 code for a 2004 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, Damaged wiring or connectors in the 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 2004 Infiniti G35 indicates HO2S12 Circuit High Voltage.
Common causes
Common causes include Faulty HO2S12 sensor, Damaged wiring or connectors in the 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 16, 2024
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Code P0138 2004 Infiniti G35 Description

The P0138 code for a 2004 Infiniti G35 indicates an issue with the HO2S12 (Heated Oxygen Sensor 1 Bank 1 Sensor 2) circuit registering high voltage. The HO2S12 sensor is responsible for monitoring the oxygen levels in the exhaust gases and sending this data to the engine control module (ECM) to adjust the air-fuel mixture for optimal combustion. When the voltage from the sensor is higher than expected, it can lead to a variety of performance issues in the vehicle.

OBDII Code P0138 2004 Infiniti G35 - HO2S12 Circuit High Voltage
P0138 2004 Infiniti G35 Code - HO2S12 Circuit High Voltage

Common Causes of P0138 2004 Infiniti G35

  1. Faulty HO2S12 sensor
  2. Damaged wiring or connectors in the sensor circuit
  3. Exhaust leaks near the sensor
  4. Issues with the ECM
  5. Contaminated sensor due to oil or coolant leaks

Symptoms of P0138 2004 Infiniti G35

  1. Decreased fuel efficiency
  2. Rough idling
  3. Hesitation during acceleration
  4. Engine misfires
  5. Check engine light illuminated on the dashboard

How to Fix P0138 2004 Infiniti G35

  1. Begin by inspecting the wiring and connectors in the HO2S12 sensor circuit for any damage or corrosion. Repair or replace as necessary.
  2. Check for exhaust leaks near the sensor that could be affecting its readings. Repair any leaks found.
  3. Test the HO2S12 sensor using a multimeter to determine if it is functioning correctly. Replace the sensor if it is faulty.
  4. Clear the diagnostic trouble codes from the ECM using a scan tool and test drive the vehicle to ensure the issue has been resolved.
  5. If the problem persists, further diagnostics may be needed to pinpoint the exact cause of the high voltage reading.

Cost to Fix P0138 2004 Infiniti G35

The typical repair costs for addressing a P0138 code on a 2004 Infiniti G35 can range from $150 to $400, depending on the specific cause of the issue and the cost of parts and labor. It's important to note that diagnosis time and labor rates at auto repair shops can vary, so it's advisable to check with local shops for a more accurate estimate. Additionally, factors such as location, vehicle make and model, and engine type can also impact the overall repair costs.

Tech Notes for P0138 2004 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 2004 Infiniti G35 Code

1. What does OBDII code P0138 for a 2004 Infiniti G35 mean?

- OBDII code P0138 in a 2004 Infiniti G35 indicates a high voltage condition in the HO2S12 oxygen sensor circuit.

2. What are the common symptoms of OBDII code P0138 in a 2004 Infiniti G35?

- Common symptoms of P0138 in a 2004 Infiniti G35 include poor fuel efficiency, rough idling, and potential engine misfires.

3. What are the possible causes of OBDII code P0138 in a 2004 Infiniti G35?

- Possible causes of P0138 in a 2004 Infiniti G35 include a faulty oxygen sensor, wiring issues in the sensor circuit, or a problem with the engine control module.

4. How can I diagnose the HO2S12 circuit high voltage issue in my 2004 Infiniti G35?

- Diagnosing the P0138 code in a 2004 Infiniti G35 involves testing the oxygen sensor, inspecting the wiring for damage, and checking the engine control module for faults.

5. Can a dirty air filter trigger OBDII code P0138 in a 2004 Infiniti G35?

- While a dirty air filter may impact engine performance, it is not a direct cause of the HO2S12 circuit high voltage issue indicated by code P0138.

6. How serious is OBDII code P0138 in a 2004 Infiniti G35?

- OBDII code P0138 should be addressed promptly as it can lead to decreased fuel efficiency and potential damage to the catalytic converter over time.

7. Can I continue driving my 2004 Infiniti G35 with OBDII code P0138?

- It is not recommended to continue driving your 2004 Infiniti G35 with OBDII code P0138 as it can affect engine performance and emissions.

8. What are the repair options for resolving OBDII code P0138 in a 2004 Infiniti G35?

- Repair options for P0138 in a 2004 Infiniti G35 include replacing the oxygen sensor, repairing damaged wiring, or addressing any issues with the engine control module.

9. How much does it typically cost to fix OBDII code P0138 in a 2004 Infiniti G35?

- The cost of fixing P0138 in a 2004 Infiniti G35 can vary depending on the specific issue, but it may range from $100 to $500 for parts and labor.

10. Can I reset the OBDII code P0138 in my 2004 Infiniti G35 myself?

- While you can reset the code using an OBDII scanner, it is important to address the underlying issue causing P0138 to prevent it from recurring.

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