AutoCodes – Nissan – P0138 2006 Nissan Altima Sedan

P0138 2006 Nissan Altima Sedan 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 Altima Sedan 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 5,240

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

What does this mean?

What are the Possible Causes of the DTC P0138 2006 Nissan Altima Sedan?

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 Altima Sedan?

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 Altima Sedan 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 Altima Sedan Code

1. What are the common symptoms of OBDII code P0138 in a 2006 Nissan Altima Sedan?

- Common symptoms include poor fuel economy, rough idling, and possible stalling of the vehicle.

2. What does the HO2S12 Circuit High Voltage error code mean for a 2006 Nissan Altima Sedan?

- This code indicates that the oxygen sensor (HO2S12) in bank 1 sensor 2 is registering a high voltage condition.

3. What are the possible causes of the P0138 code in a 2006 Nissan Altima Sedan?

- The code can be triggered by issues such as a faulty oxygen sensor, a wiring problem in the sensor circuit, or an engine running too rich.

4. How can I diagnose the HO2S12 Circuit High Voltage error code in my 2006 Nissan Altima Sedan?

- To diagnose this code, you may need to inspect the oxygen sensor, check the sensor's wiring and connections, and perform a scan tool test to monitor sensor data.

5. Can a dirty or contaminated oxygen sensor cause the P0138 code in a 2006 Nissan Altima Sedan?

- Yes, a dirty or contaminated oxygen sensor can lead to improper readings and trigger the high voltage error code.

6. Is it safe to continue driving my 2006 Nissan Altima Sedan with the P0138 code present?

- It is not recommended to drive the vehicle with the P0138 code active, as it can lead to poor engine performance and potential damage over time.

7. How can I reset the OBDII code P0138 in my 2006 Nissan Altima Sedan after making repairs?

- You can reset the code using an OBDII scanner or by disconnecting the car's battery for a few minutes to clear the error code.

8. What are some repair tips for fixing the HO2S12 Circuit High Voltage issue in a 2006 Nissan Altima Sedan?

- Repair tips include replacing the faulty oxygen sensor, checking and repairing any damaged wiring, and ensuring proper sensor connections.

9. Will replacing the oxygen sensor fix the P0138 code in my 2006 Nissan Altima Sedan?

- In many cases, replacing the oxygen sensor responsible for the high voltage condition can resolve the P0138 code issue.

10. How can I prevent the OBDII code P0138 from recurring in my 2006 Nissan Altima Sedan?

- To prevent the P0138 code from coming back, it's essential to perform regular maintenance, use quality fuel, and address any engine issues promptly.