P0138 GMC Code - HO2S Circuit High Voltage Bank 1 Sensor 2
Quick Answer
The P0138 GMC code refers to a problem with the HO2S (heated oxygen sensor) Circuit High Voltage for Bank 1 Sensor 2. Common causes include Faulty Oxygen Sensor: The most common cause of this code is a faulty HO2S sensor itself, which may need to be replaced, Wiring Issues: Problems with the wiring connecting the oxygen sensor to the ECM can also trigger this code, Exhaust Leaks: Leaks in the exhaust system can introduce outside air into the system, affecting the readings of the oxygen sensor. 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
- P0138 GMC indicates HO2S Circuit High Voltage Bank 1 Sensor 2.
- Common causes
- Common causes include Faulty Oxygen Sensor: The most common cause of this code is a faulty HO2S sensor itself, which may need to be replaced, Wiring Issues: Problems with the wiring connecting the oxygen sensor to the ECM can also trigger this code, Exhaust Leaks: Leaks in the exhaust system can introduce outside air into the system, affecting the readings of the oxygen sensor.
- 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.
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Code P0138 GMC Description
The P0138 GMC code refers to a problem with the HO2S (heated oxygen sensor) Circuit High Voltage for Bank 1 Sensor 2. This sensor is responsible for monitoring the oxygen levels in the exhaust gases as they leave the engine. The data collected by the sensor is crucial for the engine control module (ECM) to adjust the air-fuel mixture for optimal performance and fuel efficiency.
Common Causes of P0138 GMC
- Faulty Oxygen Sensor: The most common cause of this code is a faulty HO2S sensor itself, which may need to be replaced.
- Wiring Issues: Problems with the wiring connecting the oxygen sensor to the ECM can also trigger this code.
- Exhaust Leaks: Leaks in the exhaust system can introduce outside air into the system, affecting the readings of the oxygen sensor.
- ECM Failure: In rare cases, a malfunctioning engine control module (ECM) can cause issues with the oxygen sensor readings.
- Rich or Lean Fuel Mixture: A rich or lean air-fuel mixture can also impact the oxygen sensor's readings and trigger this code.
Symptoms of P0138 GMC
- Check Engine Light: The most common symptom associated with this code is the illumination of the check engine light on the vehicle's dashboard.
- Poor Fuel Economy: A malfunctioning oxygen sensor can cause the engine to run rich or lean, resulting in decreased fuel efficiency.
- Rough Idling: The engine may experience rough idling or hesitation when the oxygen sensor is not functioning properly.
- Emission Issues: A faulty oxygen sensor can lead to increased emissions, potentially causing the vehicle to fail emissions tests.
- Reduced Engine Performance: The engine may lack power and responsiveness when the oxygen sensor is not providing accurate data to the ECM.
How to Fix P0138 GMC
- Diagnose the Issue: Use a scan tool to read the code and determine the exact cause of the problem.
- Inspect Wiring: Check the wiring connecting the oxygen sensor to the ECM for any signs of damage or corrosion.
- Replace Oxygen Sensor: If the sensor is faulty, it will need to be replaced with a new one.
- Clear Codes: After the repair is complete, clear the codes from the ECM to turn off the check engine light.
- Test Drive: Take the vehicle for a test drive to ensure that the issue has been resolved and that the check engine light does not come back on.
Cost to Fix P0138 GMC
The cost of repairing a P0138 GMC code can vary depending on the specific cause of the issue. In general, the cost of replacing an oxygen sensor can range from $100 to $300, including parts and labor. However, additional costs may be incurred if wiring repairs or ECM replacement is necessary. It's important to note that labor rates at auto repair shops can vary, with rates typically ranging from $80 to $150 per hour. Additionally, the cost of parts can vary based on the vehicle make and model. For a more accurate estimate, it's recommended to consult with a local auto repair shop.
Tech Notes for P0138 GMC
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Information for Specific GMC Models
- P0138 2014 GMC Sierra — HO2S Circuit High Voltage Bank 1 Sensor 2
- P0138 2015 GMC Sierra — HO2S Circuit High Voltage Bank 1 Sensor 2
- P0138 2016 GMC Sierra — HO2S Circuit High Voltage Bank 1 Sensor 2
- P0138 2017 GMC Sierra — HO2S Circuit High Voltage Bank 1 Sensor 2
- P0138 2018 GMC Sierra — HO2S Circuit High Voltage Bank 1 Sensor 2
Frequently Asked Questions about P0138 GMC Code
No Frequently Asked Questions about P0138 GMC Code found.
Discuss the causes and fixes for P0138 GMC OBDII Code
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What model and year is your vehicle?
The Rear Heated Oxygen Sensor Bank 1 is the most common cause for the P0138 code.
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