Engine-CodesBuick – P1138 Buick

P1138 Buick Code - HO2S Circuit High Voltage Sensor 2

Quick Answer

The P1138 Buick code indicates a problem with the HO2S (heated oxygen sensor) Circuit High Voltage Sensor 2. Common causes include Faulty HO2S sensor, Wiring issues such as corrosion or short circuits, ECM malfunction. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P1138 Buick indicates HO2S Circuit High Voltage Sensor 2.
Common causes
Common causes include Faulty HO2S sensor, Wiring issues such as corrosion or short circuits, ECM malfunction.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Table of contents Created and updated by William Orellana on Sep 08, 2024
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Code P1138 Buick Description

The P1138 Buick code indicates a problem with the HO2S (heated oxygen sensor) Circuit High Voltage Sensor 2. The heated oxygen sensor is responsible for monitoring the oxygen levels in the exhaust gases and providing this information to the engine control module (ECM) for proper air-fuel ratio adjustment. Sensor 2 refers to the second oxygen sensor in the exhaust system, typically located downstream of the catalytic converter.

OBDII Code P1138 Buick - HO2S Circuit High Voltage Sensor 2
P1138 Buick Code - HO2S Circuit High Voltage Sensor 2

Common Causes of P1138 Buick

  1. Faulty HO2S sensor
  2. Wiring issues such as corrosion or short circuits
  3. ECM malfunction
  4. Exhaust leaks near the oxygen sensor
  5. Fuel system issues such as a clogged fuel filter

Symptoms of P1138 Buick

  1. Check Engine Light illuminated on the dashboard
  2. Decreased fuel efficiency
  3. Rough idling or stalling
  4. Engine hesitation or lack of power
  5. Increased emissions

How to Fix P1138 Buick

  1. Use an OBD-II scanner to confirm the P1138 code and identify which oxygen sensor is causing the issue.
  2. Inspect the wiring harness connected to the oxygen sensor for any damage or corrosion. Repair or replace as needed.
  3. Test the oxygen sensor using a multimeter to check for proper voltage readings. Replace the sensor if it is faulty.
  4. Clear the error code with the OBD-II scanner and drive the vehicle to monitor for any recurrence of the issue.
  5. If the problem persists, further diagnostics may be needed to check for ECM issues or other underlying problems.

Cost to Fix P1138 Buick

The typical repair costs for addressing the P1138 Buick code can range from $150 to $400, including parts and labor. However, the specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. It's advisable to check local rates for a more precise estimate. Keep in mind that rates in metropolitan areas or at dealerships may be higher, while independent shops often charge less for labor.

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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.

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