P0043 Subaru Code - HO2S13 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 1 Sensor 3, Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3 harness is open shorted, Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3 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
- P0043 Subaru indicates HO2S13 Heater Control Circuit Low.
- Common causes
- Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3, Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3 harness is open shorted, Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3 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 P0043 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 P0043 Subaru?
- Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3 harness is open shorted
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3 circuit poor electrical connection
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 3 fuse
- Faulty Engine Control Module (ECM)
How to Fix the DTC P0043 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
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0043 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 P0043 Subaru Code
What does the OBDII code P0043 mean for a Subaru?
Code P0043 indicates a problem in the heater control circuit for the downstream oxygen sensor (HO2S13), often caused by an electrical issue or a failed sensor.
What are common symptoms of P0043 in a Subaru?
Symptoms may include an illuminated check engine light, increased fuel consumption, poor engine performance, or difficulty passing an emissions test.
What causes the P0043 code to appear on a Subaru?
Common causes include a faulty oxygen sensor, damaged wiring or connectors, a blown fuse, or issues with the engine control module (ECM).
How can I diagnose the P0043 code on my Subaru?
Start by inspecting the oxygen sensor wiring and connectors for damage, check for blown fuses, and test the resistance of the heater circuit using a multimeter.
Can I drive my Subaru with the P0043 code?
While the vehicle may still be drivable, ignoring the code can lead to reduced fuel efficiency and engine performance, as well as potential damage to other components.
How do I fix the P0043 code on my Subaru?
Repairs may include replacing the faulty oxygen sensor, repairing damaged wiring or connectors, or replacing a blown fuse related to the heater circuit.
How much does it cost to fix the P0043 code on a Subaru?
The cost can range from $150-$400 depending on whether the oxygen sensor needs replacement or if wiring repairs are required.
Can a faulty ECM cause the P0043 code on a Subaru?
Yes, although less common, a malfunctioning ECM can fail to properly regulate the heater circuit, leading to the P0043 code.
How can I prevent the P0043 code from reoccurring on my Subaru?
Regular maintenance, including inspecting wiring and connectors for damage and replacing worn-out oxygen sensors, can help prevent this issue.
Will clearing the P0043 code fix the problem on my Subaru?
Clearing the code will remove it temporarily, but unless the underlying issue is resolved, the code is likely to return.
Discuss the causes and fixes for P0043 Subaru OBDII Code
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