AutoCodes – Nissan – P0051 Nissan

P0051 Nissan Code - HO2S21 Heater Control Circuit Low

Quick Answer

Oxygen Sensors (O2S) or Heated Oxygen Sensors (HO2S) need to reach a minimum operating temperature of 750 degrees F to produce an accurate voltage signal. Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 harness is open shorted, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 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: P0051 Nissan indicates HO2S21 Heater Control Circuit Low.
Common causes: Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 harness is open shorted, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 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 50,888

How popular is this code, among other codes? Medium

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 Mar 23, 2024

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0051 Nissan Description

Oxygen Sensors (O2S) or Heated Oxygen Sensors (HO2S) need to reach a minimum operating temperature of 750 degrees F to produce an accurate voltage signal. The faster the heated oxygen sensor reaches that temperature the faster the sensor will start sending an accurate signal to the Engine Control Module (ECM).
In order to achieve the require temperature, a heater element is included inside the heated oxygen sensor. The ECM controls the heated oxygen sensor heater element based on signals from the engine coolant temperature and engine load. The ECM controls the heater element circuit by allowing current flow to ground.
The ECM monitors the voltage signal received through the heater element circuit and determines the state of the circuit by comparing the voltage detected with the factory specifications.

OBDII Code P0051 Nissan - HO2S21 Heater Control Circuit Low - AutoCodes.com — P0051 Nissan Code - HO2S21 Heater Control Circuit Low

What does this mean?

What are the Possible Causes of the DTC P0051 Nissan?

Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1
Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 harness is open shorted
Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 circuit poor electrical connection
Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 fuse
Faulty Engine Control Module (ECM)

How to Fix the DTC P0051 Nissan?

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

The code means that there is a problem with the heater element circuit of the heated oxygen sensor. Water getting inside the heated oxygen sensor connector can caused the heated oxygen sensor fuse to blow, which is a very common problem for this type codes. Before replacing the sensor, check for the condition of the heated oxygen sensor fuse and connectors.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0051 Nissan 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 P0051 Nissan code?

Need more information on how to fix the P0051 Nissan code? Get Access to Factory Service Manuals

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Information for Specific Nissan Models

P0051 2006 Nissan Maxima — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
P0051 2007 Nissan Maxima — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
P0051 2008 Nissan Maxima — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
P0051 2006 Nissan Pathfinder — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
P0051 2007 Nissan Pathfinder — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
P0051 2008 Nissan Pathfinder — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
P0051 2009 Nissan Pathfinder — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
P0051 2010 Nissan Pathfinder — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
P0051 2011 Nissan Pathfinder — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
P0051 2012 Nissan Pathfinder — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
P0051 2002 Nissan Sentra — HO2S21 Heater Control Circuit Low
P0051 2007 Nissan Sentra — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
P0051 2008 Nissan Sentra — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
P0051 2009 Nissan Sentra — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
P0051 2010 Nissan Sentra — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
P0051 2011 Nissan Sentra — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
P0051 2012 Nissan Sentra — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low

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 P0051 Nissan Code

1. What are the common symptoms of OBDII code P0051 in a Nissan?

- Common symptoms include decreased fuel efficiency, rough idling, engine misfires, and the illumination of the Check Engine light.

2. What does the OBDII code P0051 indicate in a Nissan?

- OBDII code P0051 for a Nissan indicates a malfunction in the HO2S21 (Heated Oxygen Sensor Bank 2 Sensor 1) heater control circuit, specifically a low voltage condition.

3. What are the potential causes of OBDII code P0051 in a Nissan?

- Potential causes include a faulty HO2S21 sensor, damaged wiring or connectors in the heater circuit, a blown fuse, or a malfunction in the ECM (Engine Control Module).

4. How can I diagnose the OBDII code P0051 in my Nissan?

- Diagnosis typically involves using an OBDII scanner to read the code, then testing the HO2S21 sensor and its heater circuit for proper functionality using a multimeter.

5. Is it safe to continue driving my Nissan with OBDII code P0051 present?

- It is generally not recommended to drive the vehicle with a P0051 code as it can lead to decreased fuel efficiency, potential engine damage, and increased emissions.

6. How can I repair OBDII code P0051 in my Nissan?

- Repair options may include replacing the HO2S21 sensor, repairing damaged wiring or connectors, checking and replacing fuses if necessary, or addressing any ECM issues.

7. Can a DIY enthusiast fix OBDII code P0051 in a Nissan?

- Depending on the individual's skill level and access to tools, a DIY enthusiast may be able to address the issue by following a repair manual or online guides detailing the necessary steps.

8. Are there any preventive measures to avoid OBDII code P0051 in a Nissan?

- Regular vehicle maintenance, such as inspecting and replacing oxygen sensors at recommended intervals, can help prevent issues that may trigger the P0051 code.

9. How long does it typically take to repair OBDII code P0051 in a Nissan?

- The repair time can vary based on the exact cause of the issue, but it may take anywhere from 1 to 3 hours to diagnose and fix the problem, assuming all necessary parts are readily available.

10. Can clearing the OBDII code P0051 in a Nissan make it go away permanently?

- Clearing the code without addressing the underlying issue will not make it go away permanently. The problem causing the P0051 code needs to be diagnosed and fixed to prevent it from recurring.