AutoCodes – Infiniti – P0138 2006 Infiniti G35

P0138 2006 Infiniti G35 Code - HO2S12 Circuit High Voltage

Quick Answer

The Heated Oxygen Sensor 2 (HO2S) (Rear O2 Sensor), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. Common causes include Faulty Rear Heated Oxygen Sensor Bank 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection. 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 2006 Infiniti G35 indicates HO2S12 Circuit High Voltage.
Common causes: Common causes include Faulty Rear Heated Oxygen Sensor Bank 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection.
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.

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Code Popularity 4,354

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Apr 01, 2024

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0138 2006 Infiniti G35 Description

The Heated Oxygen Sensor 2 (HO2S) (Rear O2 Sensor), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. For optimum catalyst operation, the air fuel mixture (air-fuel ratio) must be maintained near the ideal stoichiometric ratio. The HO2S output voltage changes suddenly in the vicinity of the stoichiometric ratio. The Engine Control Module (ECM) adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric. The HO2S generates a voltage between 0.1 and 0.9 V in response to oxygen in the exhaust gas. If the oxygen in the exhaust gas increases, the air-fuel ratio becomes Lean. The ECM interprets Lean when the HO2S voltage is below 0.45 V. If the oxygen in the exhaust gas decreases, the air-fuel ratio becomes Rich. The ECM interprets Rich when the HO2S voltage is above 0.45 V.

OBDII Code P0138 2006 Infiniti G35 - HO2S12 Circuit High Voltage - AutoCodes.com — P0138 2006 Infiniti G35 Code - HO2S12 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0138 2006 Infiniti G35?

Faulty Rear Heated Oxygen Sensor Bank 1
Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
Intake air leaks
Exhaust gas leaks
Inappropriate fuel pressure
Faulty fuel injectors

How to Fix the DTC P0138 2006 Infiniti G35?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

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

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0138 2006 Infiniti G35 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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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 2006 Infiniti G35 Code

1. What are the common symptoms of OBDII code P0138 on a 2006 Infiniti G35?

- The common symptoms include poor fuel economy, rough idling, engine misfires, and potentially an illuminated Check Engine Light.

2. What does the OBDII code P0138 "HO2S12 Circuit High Voltage" mean on a 2006 Infiniti G35?

- It indicates that the downstream oxygen sensor (HO2S12) in bank 1 sensor 2 is detecting a high voltage condition consistently.

3. What are the possible causes of OBDII code P0138 on a 2006 Infiniti G35?

- The causes may include a faulty oxygen sensor, damaged wiring or connectors in the sensor circuit, exhaust leaks, or issues with the engine's fuel system.

4. How can I diagnose the OBDII code P0138 on my 2006 Infiniti G35?

- You can diagnose the code by performing a visual inspection of the oxygen sensor and its wiring, checking for exhaust leaks, using a scan tool to monitor sensor readings, and testing the sensor's voltage output.

5. Can I continue driving my 2006 Infiniti G35 with OBDII code P0138 present?

- It is not recommended to drive for an extended period with this code active, as it can lead to decreased fuel efficiency and potential damage to the catalytic converter.

6. How can I repair OBDII code P0138 on a 2006 Infiniti G35?

- Repair options may include replacing the downstream oxygen sensor, repairing damaged wiring or connectors, fixing any exhaust leaks, or addressing fuel system issues.

7. Are there any DIY tips for fixing OBDII code P0138 on a 2006 Infiniti G35?

- While some may attempt to replace the oxygen sensor themselves, it is recommended to consult a professional mechanic for proper diagnosis and repair of this code.

8. Will resetting the OBDII code P0138 on a 2006 Infiniti G35 make it go away permanently?

- Resetting the code may temporarily turn off the Check Engine Light, but if the underlying issue causing P0138 is not addressed, the code is likely to return.

9. How much does it typically cost to fix OBDII code P0138 on a 2006 Infiniti G35 at a repair shop?

- The cost of fixing this code can vary depending on the exact cause and parts needed, but it may range from $100 to $300 for parts and labor.

10. Can a bad oxygen sensor cause other codes besides P0138 on a 2006 Infiniti G35?

- Yes, a faulty oxygen sensor can potentially trigger other related codes such as P0139 (HO2S12 Circuit Slow Response) or codes related to fuel trim and air-fuel mixture issues.