AutoCodes – Nissan – P0138 2006 Nissan Sentra

P0138 2006 Nissan Sentra 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 Nissan Sentra 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 11,842

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 2006 Nissan Sentra 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 Nissan Sentra - HO2S12 Circuit High Voltage - AutoCodes.com — P0138 2006 Nissan Sentra Code - HO2S12 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0138 2006 Nissan Sentra?

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 Nissan Sentra?

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 Nissan Sentra 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 Nissan Sentra Code

1. What does the OBDII code P0138 on a 2006 Nissan Sentra mean?

- The code P0138 indicates a high voltage condition in the HO2S12 (Heated Oxygen Sensor Bank 1 Sensor 2) circuit of a 2006 Nissan Sentra.

2. What are the common symptoms of a P0138 code in a 2006 Nissan Sentra?

- 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 a P0138 code on a 2006 Nissan Sentra?

- The main causes of a P0138 code include a faulty HO2S12 sensor, wiring issues in the sensor circuit, exhaust leaks, or a problem with the engine's fuel system.

4. How can I diagnose a P0138 code on my 2006 Nissan Sentra?

- Diagnosis involves using an OBDII scanner to read the code, checking the wiring and connections to the HO2S12 sensor, and testing the sensor's voltage output.

5. Can I continue driving my 2006 Nissan Sentra with a P0138 code?

- It is generally not recommended to drive with a P0138 code as it can lead to decreased fuel efficiency and potential damage to the engine over time.

6. How do I repair a P0138 code on my 2006 Nissan Sentra?

- Repair options include replacing the HO2S12 sensor, repairing any damaged wiring or connections, fixing exhaust leaks, and addressing any fuel system issues.

7. Is it possible to reset the check engine light after fixing a P0138 code on a 2006 Nissan Sentra?

- Yes, you can reset the check engine light using an OBDII scanner after the issue causing the P0138 code has been resolved.

8. How much does it typically cost to fix a P0138 code on a 2006 Nissan Sentra?

- The cost of fixing a P0138 code can vary depending on the exact cause, but it may range from $100 to $300 for parts and labor.

9. Can a P0138 code on a 2006 Nissan Sentra cause emissions test failure?

- Yes, a P0138 code can cause emissions test failure due to the impact on the vehicle's emissions control system.

10. How often does a P0138 code occur in a 2006 Nissan Sentra?

- The occurrence of a P0138 code can vary, but it is not uncommon in older vehicles like the 2006 Nissan Sentra with high mileage or poor maintenance.