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Engine-Codes – Subaru – P0052 Subaru

P0052 Subaru Code - HO2S21 Heater Control Circuit High

Quick Answer

The P0052 code for Subaru vehicles specifically refers to an issue with the HO2S21 (Heated Oxygen Sensor 2 Bank 2) heater control circuit being detected as high. Common causes include Faulty HO2S21 heater element, Short or open circuit in the heater control circuit, Blown fuse related to the HO2S21 heater. 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
P0052 Subaru indicates HO2S21 Heater Control Circuit High.
Common causes
Common causes include Faulty HO2S21 heater element, Short or open circuit in the heater control circuit, Blown fuse related to the HO2S21 heater.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 07, 2024
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Code P0052 Subaru Description

The P0052 code for Subaru vehicles specifically refers to an issue with the HO2S21 (Heated Oxygen Sensor 2 Bank 2) heater control circuit being detected as high. The heated oxygen sensor plays a crucial role in monitoring the oxygen levels in the exhaust gases, helping the engine control module (ECM) adjust the air-fuel mixture for optimal combustion. The heater control circuit is responsible for ensuring that the sensor reaches operating temperature quickly to provide accurate readings.

OBDII Code P0052 Subaru - HO2S21 Heater Control Circuit High
P0052 Subaru Code - HO2S21 Heater Control Circuit High

Common Causes of P0052 Subaru

  1. Faulty HO2S21 heater element
  2. Short or open circuit in the heater control circuit
  3. Blown fuse related to the HO2S21 heater
  4. Wiring damage or corrosion
  5. ECM issue

Symptoms of P0052 Subaru

  1. Check engine light illuminated on the dashboard
  2. Decreased fuel efficiency
  3. Rough idling or stalling
  4. Poor acceleration
  5. Increased emissions

How to Fix P0052 Subaru

  1. Use an OBD-II scanner to confirm the P0052 code and identify the specific issue with the HO2S21 heater control circuit.
  2. Inspect the wiring and connections related to the HO2S21 sensor for any damage or corrosion. Repair or replace as needed.
  3. Test the HO2S21 heater element for continuity and resistance. Replace if faulty.
  4. Check and replace any blown fuses associated with the HO2S21 heater circuit.
  5. Clear the code with the OBD-II scanner and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0052 Subaru

The cost of repairing a P0052 code on a Subaru vehicle can vary depending on the specific cause of the issue and the labor rates in your area. On average, the parts for this repair, including a new heated oxygen sensor, can range from $50 to $200. Labor costs can add another $100 to $200, bringing the total repair cost to approximately $150 to $400. Keep in mind that these are rough estimates, and actual costs may differ based on your location and the shop you choose for the repair. It's recommended to obtain quotes from multiple auto repair shops to find the best price for your specific situation.

When is the Code Detected?

The P0052 is set when the ECM detects an excessively high voltage through the heated oxygen sensor heater circuit

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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 P0052 Subaru Code

1. What are the common symptoms of OBDII code P0052 on a Subaru?

The common symptoms of code P0052 include poor fuel economy, rough idling, stalling, and the illumination of the Check Engine Light.

2. What does the OBDII code P0052 Subaru indicate?

OBDII code P0052 for a Subaru indicates an issue with the HO2S21 (Heated Oxygen Sensor Bank 2 Sensor 1) heater control circuit, specifically a high voltage condition.

3. What are the potential causes of OBDII code P0052 on a Subaru?

Potential causes of code P0052 on a Subaru include a faulty HO2S21 sensor, damaged wiring or connectors in the heater circuit, a blown fuse, or a malfunctioning PCM (Powertrain Control Module).

4. How can I diagnose the OBDII code P0052 on my Subaru?

To diagnose code P0052, you can use a scan tool to check for the code, visually inspect the sensor and its wiring for any visible damage, and perform tests to check the sensor's resistance and heater circuit operation.

5. Can I still drive my Subaru with OBDII code P0052?

It is not recommended to drive your Subaru with code P0052 present, as it can lead to decreased fuel efficiency and potential engine performance issues. It is best to address the problem promptly.

6. How do I repair OBDII code P0052 on my Subaru?

Repairing code P0052 on a Subaru may involve replacing the HO2S21 sensor, repairing or replacing damaged wiring or connectors, checking and replacing fuses if necessary, and resetting the fault code.

7. How much does it cost to fix OBDII code P0052 on a Subaru?

The cost to fix code P0052 on a Subaru can vary depending on the exact cause of the issue and whether you perform the repairs yourself or take your vehicle to a mechanic. Costs may include parts, labor, and diagnostic fees.

8. Can a DIY enthusiast fix OBDII code P0052 on a Subaru?

Yes, a DIY enthusiast with the necessary tools and knowledge can potentially fix code P0052 on a Subaru. However, diagnosing and repairing electrical issues like this may require some experience and skill.

9. Will resetting the Check Engine Light clear OBDII code P0052 on a Subaru?

Resetting the Check Engine Light may temporarily clear the code, but if the underlying issue causing code P0052 is not addressed, the light is likely to come back on. It's important to diagnose and fix the problem to prevent recurrence.

10. How urgent is it to address OBDII code P0052 on a Subaru?

While code P0052 may not cause immediate drivability issues, it is important to address it in a timely manner to prevent potential long-term damage to your Subaru's engine and emissions system.

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