P0051 Infiniti 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 Infiniti 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.
Code P0051 Infiniti Description
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.
What are the Possible Causes of the DTC P0051 Infiniti?
- 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 Infiniti?
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.
Code Tech Notes
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0051 Infiniti 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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Information for Specific Infiniti Models
- P0051 2003 Infiniti G35 — HO2S21 Heater Control Circuit Low
- P0051 2004 Infiniti G35 — HO2S21 Heater Control Circuit Low
- P0051 2005 Infiniti G35 — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
- P0051 2006 Infiniti G35 — Air Fuel Ratio Sensor 1 Heater Bank 2 Control Circuit Low
Frequently Asked Questions about P0051 Infiniti Code
1. What does the OBDII code P0051 mean on an Infiniti?
P0051 indicates a problem with the Heater Control Circuit Low in the Bank 2 Sensor 1 oxygen sensor, meaning the heater element is not functioning properly.
2. What are the common symptoms of P0051 in an Infiniti?
Symptoms include poor fuel efficiency, rough idling, reduced engine performance, and an illuminated Check Engine Light.
3. What causes the P0051 code to appear on an Infiniti?
Common causes include a faulty oxygen sensor, damaged wiring or connectors, a blown fuse, or issues with the engine control module (ECM).
4. Can I drive my Infiniti with the P0051 code?
While driving with P0051 may be possible, it is not recommended as it can lead to poor fuel economy and potential damage to the catalytic converter over time.
5. How can I fix the P0051 code on my Infiniti?
Repairs may involve replacing the oxygen sensor, repairing damaged wiring, checking fuses, or diagnosing the ECM for further issues.
6. How do I locate the Bank 2 Sensor 1 oxygen sensor on my Infiniti?
Bank 2 Sensor 1 is the upstream oxygen sensor on the side of the engine opposite Cylinder 1, typically located before the catalytic converter.
7. What tools are needed to diagnose and repair the P0051 code?
You’ll need an OBDII scanner, a multimeter to check voltage and resistance, and basic tools to replace the oxygen sensor if needed.
8. How do I test the oxygen sensor heater circuit for P0051?
Use a multimeter to check the resistance of the heater circuit in the oxygen sensor; a reading outside the manufacturer’s specifications indicates a faulty sensor.
9. Will clearing the P0051 code turn off the Check Engine Light permanently?
Clearing the code will temporarily turn off the light, but if the underlying issue isn’t fixed, the code and light will return.
10. How much does it cost to repair the P0051 code on an Infiniti?
Repair costs vary, but replacing an oxygen sensor typically ranges from $150 to $400, depending on parts and labor.
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