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Engine-Codes – Subaru – P0037 Subaru

P0037 Subaru Code - HO2S12 Heater Control Circuit Low

Quick Answer

The P0037 diagnostic trouble code (DTC) for Subaru vehicles refers to a malfunction in the HO2S12 (Heated Oxygen Sensor 1, Bank 1 Sensor 2) heater control circuit. Common causes include Faulty HO2S12 heater element, Wiring or connector issues in the heater circuit, ECM software or hardware problems. 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
P0037 Subaru indicates HO2S12 Heater Control Circuit Low.
Common causes
Common causes include Faulty HO2S12 heater element, Wiring or connector issues in the heater circuit, ECM software or hardware problems.
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 Aug 30, 2024
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Code P0037 Subaru Description

The P0037 diagnostic trouble code (DTC) for Subaru vehicles refers to a malfunction in the HO2S12 (Heated Oxygen Sensor 1, Bank 1 Sensor 2) heater control circuit. This sensor is responsible for measuring the oxygen content in the exhaust gases and providing feedback to the engine control module (ECM) for proper fuel mixture adjustments. The heater control circuit is designed to bring the sensor up to operating temperature quickly for accurate readings.

OBDII Code P0037 Subaru - HO2S12 Heater Control Circuit Low
P0037 Subaru Code - HO2S12 Heater Control Circuit Low

Common Causes of P0037 Subaru

  1. Faulty HO2S12 heater element
  2. Wiring or connector issues in the heater circuit
  3. ECM software or hardware problems
  4. Corrosion or damage to the sensor or related components
  5. Electrical system issues

Symptoms of P0037 Subaru

  1. Check Engine Light (MIL) illuminated on the dashboard
  2. Poor fuel economy
  3. Rough idling or stalling
  4. Decreased engine performance
  5. Failed emissions test

How to Fix P0037 Subaru

  1. Diagnose the issue using a scan tool to confirm the P0037 code and check for related codes
  2. Inspect the wiring, connectors, and sensor for any visible damage or corrosion
  3. Test the heater element resistance and voltage to determine if it is functioning properly
  4. Replace the HO2S12 sensor if the heater element is faulty
  5. Clear the DTC and perform a test drive to verify the repair

Cost to Fix P0037 Subaru

The cost of repairing a P0037 code on a Subaru vehicle can vary depending on the specific model and year. In general, replacing the HO2S12 sensor can cost between $150 and $300, including parts and labor. Additional costs may apply if there are wiring or connector issues that need to be addressed. It's recommended to consult with a qualified mechanic or dealership for a more accurate estimate based on your vehicle's needs.

What does this mean?

Tech Notes for P0037 Subaru

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 cause the heated oxygen sensor fuse to blow, which is a very common problem for this type of codes. Before replacing the sensor, check for the condition of the heated oxygen sensor fuse and connectors.









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When is the Code Detected?

The P0037 is set when the ECM detects an excessively low 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 P0037 Subaru Code

1. What are the common symptoms of OBDII code P0037 on a Subaru related to the HO2S12 heater control circuit low?

The common symptoms include poor fuel economy, rough idling, stalling, and the illumination of the check engine light.

2. What are the potential causes of OBDII code P0037 on a Subaru indicating a HO2S12 heater control circuit low?

Possible causes include a faulty oxygen sensor, damaged wiring, a blown fuse, or a problem with the ECM (engine control module).

3. How can I diagnose the OBDII code P0037 on my Subaru for the HO2S12 heater control circuit low?

To diagnose this code, you can start by checking the oxygen sensor's wiring and connections, testing the sensor's resistance, inspecting the fuse, and scanning the ECM for any related trouble codes.

4. What are the recommended repair tips for resolving OBDII code P0037 on a Subaru due to a HO2S12 heater control circuit low?

Repair tips may include replacing the faulty oxygen sensor, repairing damaged wiring, checking and replacing the fuse if necessary, and clearing the trouble codes with a scan tool.

5. Can driving with OBDII code P0037 related to the HO2S12 heater control circuit low on a Subaru cause any further damage?

Continuing to drive with this code may lead to decreased fuel efficiency and potential damage to the catalytic converter over time, so it is recommended to address the issue promptly.

6. How much does it typically cost to repair OBDII code P0037 on a Subaru caused by a HO2S12 heater control circuit low?

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

7. Is it safe to drive my Subaru with the check engine light on due to OBDII code P0037 indicating a HO2S12 heater control circuit low?

While it may be safe to drive in the short term, it is advisable to address the issue promptly to prevent potential long-term damage and ensure optimal vehicle performance.

8. How long does it usually take to repair OBDII code P0037 on a Subaru related to the HO2S12 heater control circuit low?

The repair time can vary depending on the exact cause of the code and the availability of parts, but it typically takes around 1-2 hours for a professional technician to diagnose and fix the issue.

9. Can I reset the check engine light myself after resolving OBDII code P0037 on my Subaru caused by a HO2S12 heater control circuit low?

Yes, you can typically reset the check engine light by using an OBDII scanner or disconnecting the car's battery for a few minutes. If the issue is resolved, the light should reset.

10. Will OBDII code P0037 on a Subaru for the HO2S12 heater control circuit low pass during an emissions test once repaired?

After resolving the issue and resetting the check engine light, the code should not reappear during an emissions test, assuming the repair was successful and the vehicle's emissions system is functioning properly.

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