AutoCodes – Nissan – P0138 2007 Nissan Sentra

P0138 2007 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 2007 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.

Save to My Repairs Step-by-Step Diagnostic Guide My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 4,446

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
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P0138 2007 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 2007 Nissan Sentra - HO2S12 Circuit High Voltage - AutoCodes.com — P0138 2007 Nissan Sentra Code - HO2S12 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0138 2007 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 2007 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 2007 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.

Need more information about the P0138 2007 Nissan Sentra code?

Need more information on how to fix the P0138 2007 Nissan Sentra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0138 2007 Nissan Sentra code diagnosed by a professional: Find a repair shop in your area

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 2007 Nissan Sentra Code

1. What does the OBDII code P0138 on a 2007 Nissan Sentra mean?

The P0138 code relates to a high voltage condition in the HO2S12 (Heated Oxygen Sensor Bank 1 Sensor 2) circuit of a 2007 Nissan Sentra.

2. What are common symptoms of the P0138 code in a 2007 Nissan Sentra?

Common symptoms include poor fuel economy, rough idling, stalling, or a check engine light illuminating on the dashboard.

3. What are possible causes of the P0138 code in a 2007 Nissan Sentra?

Potential causes include a faulty oxygen sensor, wiring issues in the sensor circuit, exhaust leaks, or an engine running rich.

4. How can I diagnose the P0138 code on my 2007 Nissan Sentra?

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

5. Can I drive my 2007 Nissan Sentra with the P0138 code?

It's not recommended to drive for an extended period with the P0138 code as it can lead to poor engine performance and potentially cause further damage.

6. How do I repair the P0138 code on my 2007 Nissan Sentra?

Repair options may include replacing the HO2S12 sensor, repairing any wiring issues, fixing exhaust leaks, or addressing any underlying issues causing the high voltage condition.

7. Is it possible to reset the P0138 code on a 2007 Nissan Sentra without fixing the underlying issue?

While clearing the code may temporarily turn off the check engine light, the problem will likely resurface if the root cause is not addressed.

8. Is the P0138 code a serious issue in a 2007 Nissan Sentra?

Ignoring the P0138 code can lead to decreased fuel efficiency, engine performance issues, and potential damage to the catalytic converter over time.

9. How much does it typically cost to fix the P0138 code on a 2007 Nissan Sentra?

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

10. Can I prevent the P0138 code from appearing on my 2007 Nissan Sentra in the future?

Regular maintenance, such as replacing oxygen sensors at recommended intervals and addressing engine performance issues promptly, can help prevent the recurrence of the P0138 code.