P0038 Subaru Code - HO2S12 Heater Control Circuit High
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 1 Sensor 2, Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 fuse, Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 harness is open or shorted. 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
- P0038 Subaru indicates HO2S12 Heater Control Circuit High.
- Common causes
- Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2, Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 fuse, Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 harness is open or shorted.
- 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 P0038 Subaru 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 P0038 Subaru?
- Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 fuse
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 harness is open or shorted
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 circuit poor electrical connection
- Faulty Engine Control Module (ECM)
How to Fix the DTC P0038 Subaru?
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
User Submitted Video
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0038 Subaru 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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Frequently Asked Questions about P0038 Subaru Code
1. What does OBDII code P0038 mean on a Subaru?
P0038 indicates a problem with the heater control circuit of the downstream oxygen sensor (HO2S12), specifically that the circuit voltage is higher than expected.
2. What are the common symptoms of code P0038 in a Subaru?
Symptoms may include an illuminated check engine light, reduced fuel efficiency, failed emissions tests, and difficulty passing an inspection.
3. What causes the P0038 code to appear on a Subaru?
Common causes include a faulty oxygen sensor, damaged wiring or connectors in the heater circuit, or a malfunctioning engine control module (ECM).
4. Can I drive my Subaru with a P0038 code?
While it may be safe to drive for a short period, ignoring P0038 can lead to poor fuel economy and potential damage to the catalytic converter over time.
5. How do I diagnose the P0038 code on my Subaru?
Diagnose by checking the oxygen sensor's heater circuit for voltage, inspecting wiring and connectors for damage, and testing the sensor itself for functionality.
6. How do I fix the P0038 code on a Subaru?
Repairs may include replacing the downstream oxygen sensor, repairing or replacing damaged wiring, or addressing issues with the ECM.
7. How much does it cost to fix a P0038 code on a Subaru?
The cost varies but typically ranges from $100 to $300 for parts and labor, depending on whether the oxygen sensor or wiring needs replacement.
8. Can a bad oxygen sensor cause the P0038 code in my Subaru?
Yes, a faulty downstream oxygen sensor is a common cause of this code, as it may fail to properly heat or send the correct signals.
9. Does a P0038 code affect fuel efficiency in a Subaru?
Yes, a malfunctioning oxygen sensor can lead to improper air-fuel mixture adjustments, reducing fuel efficiency.
10. Do I need to clear the P0038 code after repairs on my Subaru?
Yes, after completing repairs, clear the code with an OBDII scanner and test drive the vehicle to ensure the issue is resolved.
Discuss the causes and fixes for P0038 Subaru OBDII Code
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After much troubleshooting, and searching for answers for why P0038 would not disappear on my 04 Outback, and light remained ON no matter what sensor was changed or after checking for air leaks, nothing, nothing, nothing worked... ECU needed to be replaced!!! Its gone now... Light is off... car driven for 300 miles, Catalyst finally ready and Inspection done! Subaru Has ECU issues... the computer goes bad for whatever reason. No one has videos or discusses what that reason is. I will open the old one up, to find out what happened to the old one. Purchased ECU on ebay, used. Was lucky it didnt have issues, and it worked! Hope this helps!!!
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