AutoCodes – Nissan – P0138 2005 Nissan Maxima

P0138 2005 Nissan Maxima 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 2005 Nissan Maxima 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 7,356

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 Jun 14, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0138 2005 Nissan Maxima 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 2005 Nissan Maxima - HO2S12 Circuit High Voltage - AutoCodes.com — P0138 2005 Nissan Maxima Code - HO2S12 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0138 2005 Nissan Maxima?

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 2005 Nissan Maxima?

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 2005 Nissan Maxima 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 2005 Nissan Maxima Code

1. What are the common symptoms of OBDII code P0138 in a 2005 Nissan Maxima?

- 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 error code mean in a 2005 Nissan Maxima?

- The code P0138 indicates that the oxygen sensor (O2 sensor) located in bank 1, sensor 2 is reading a high voltage condition.

3. What are the possible causes of the HO2S12 Circuit High Voltage error code in a 2005 Nissan Maxima?

- Possible causes include a faulty oxygen sensor, damaged wiring or connectors, exhaust leaks, engine misfires, or issues with the engine's fuel system.

4. How can I diagnose the HO2S12 Circuit High Voltage error code in my 2005 Nissan Maxima?

- Diagnosing the issue involves using an OBDII scanner to read the code, inspecting the oxygen sensor and its connections, checking for exhaust leaks, and testing related components.

5. Can I drive my 2005 Nissan Maxima with the P0138 code?

- It's generally safe to drive the vehicle with the P0138 code, but it's recommended to address the issue promptly to prevent potential damage to the engine and ensure optimal performance.

6. How do I repair the HO2S12 Circuit High Voltage error code in my 2005 Nissan Maxima?

- Repair options include replacing the oxygen sensor, repairing damaged wiring or connectors, fixing exhaust leaks, addressing engine misfires, or resolving fuel system issues.

7. Will resetting the check engine light fix the P0138 code in my 2005 Nissan Maxima?

- Simply resetting the check engine light will not fix the underlying issue causing the P0138 code. It's important to diagnose the problem and make necessary repairs to clear the code.

8. How much does it cost to fix the HO2S12 Circuit High Voltage error code in a 2005 Nissan Maxima?

- The cost of fixing the P0138 code can vary depending on the specific issue causing it. Costs may include the price of a new oxygen sensor, labor for repairs, and any additional parts needed.

9. Can a DIY enthusiast repair the P0138 code in a 2005 Nissan Maxima?

- Depending on the root cause of the code, some DIY enthusiasts with automotive repair experience may be able to address the issue themselves by replacing the oxygen sensor or fixing wiring problems.

10. How often does the HO2S12 Circuit High Voltage error code occur in a 2005 Nissan Maxima?

- The frequency of the P0138 code occurrence can vary. It's essential to address the issue promptly once it appears to prevent further complications and ensure the vehicle operates efficiently.