Have you ever experienced a Subaru P0138 code? This code indicates a problem with the O2 Sensor Circuit High Voltage on Bank 1 Sensor 2. This code is triggered when the rear oxygen sensor output voltage is higher than 1.2 V during normal operating conditions. Without the proper voltage, your Subaru can suffer from decreased engine performance, increased fuel consumption, or even engine stalling. To prevent this, it is important to understand what causes this code and the potential solutions. In this article, we will explore the causes and solutions to the Subaru P0138 code.
Causes and Solutions for Subaru P0138 Code
| Causes | Solutions |
|---|---|
| Water in the front oxygen sensor connector or coupling connector | Replace the front oxygen sensor connector or coupling connector |
| Wiring harness between ECM and rear oxygen sensor connector needs repair | Repair the wiring harness between ECM and rear oxygen sensor connector |
| Loose or damaged exhaust system parts | Tighten or replace any loose or damaged exhaust system parts |
| Defective rear oxygen sensor | Replace the rear oxygen sensor |
Water in the Oxygen Sensor Connector or Coupling Connector
One of the possible causes of a Subaru P0138 code is water in the front oxygen sensor connector or coupling connector. This can happen if the connector or coupling is exposed to moisture or water, causing a short or open circuit in the rear oxygen sensor. To fix this issue, the front oxygen sensor connector or coupling connector needs to be replaced.
Faulty Wiring Harness
Another possible cause of a Subaru P0138 code is a faulty wiring harness between the ECM and the rear oxygen sensor connector. If the wiring harness is not functioning correctly, it can cause a high voltage reading on the rear oxygen sensor. To fix this issue, the wiring harness between the ECM and the rear oxygen sensor connector needs to be repaired.
Loose or Damaged Exhaust System Parts
A Subaru P0138 code can also be triggered by loose or damaged exhaust system parts. If the exhaust system is not functioning correctly, it can cause a high voltage reading on the rear oxygen sensor as well. To fix this issue, any loose or damaged exhaust system parts should be tightened or replaced.
Defective Rear Oxygen Sensor
The final possible cause of a Subaru P0138 code is a defective rear oxygen sensor. If the rear oxygen sensor is not functioning correctly, it can cause a high voltage reading. To fix this issue, the rear oxygen sensor needs to be replaced.
Conclusion
A Subaru P0138 code can be triggered by a variety of causes, such as water in the oxygen sensor connector or coupling connector, a faulty wiring harness, loose or damaged exhaust system parts, or a defective rear oxygen sensor. To prevent this code from occurring, it is important to understand what causes it and the potential solutions. By understanding the causes and solutions of the Subaru P0138 Code, you can ensure that your Subaru is running in optimal condition.
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