Engine-CodesIsuzu – P0138 Isuzu

P0138 Isuzu Code - HO2S Circuit Low Voltage Sensor 2

Quick Answer

The P0138 code for Isuzu vehicles indicates a problem with the HO2S (Heated Oxygen Sensor) Circuit Low Voltage Sensor 2. Common causes include Faulty HO2S sensor, Wiring issues (shorts, frayed wires), Exhaust leaks. 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 Isuzu indicates HO2S Circuit Low Voltage Sensor 2.
Common causes
Common causes include Faulty HO2S sensor, Wiring issues (shorts, frayed wires), Exhaust leaks.
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.
Table of contents Created and updated by William Orellana on Sep 12, 2024
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Code P0138 Isuzu Description

The P0138 code for Isuzu vehicles indicates a problem with the HO2S (Heated Oxygen Sensor) Circuit Low Voltage Sensor 2. This sensor is responsible for monitoring the oxygen levels in the exhaust gases and providing feedback to the engine control module (ECM) to adjust the air-fuel mixture for optimal combustion. When the voltage from the sensor is lower than expected, it can lead to issues with fuel efficiency, emissions, and overall engine performance.

OBDII Code P0138 Isuzu - HO2S Circuit Low Voltage Sensor 2
P0138 Isuzu Code - HO2S Circuit Low Voltage Sensor 2

Common Causes of P0138 Isuzu

  1. Faulty HO2S sensor
  2. Wiring issues (shorts, frayed wires)
  3. Exhaust leaks
  4. ECM malfunction
  5. Fuel system problems

Symptoms of P0138 Isuzu

  1. Decreased fuel efficiency
  2. Rough idling or stalling
  3. Engine misfires
  4. Check Engine Light illuminated
  5. Failed emissions test

How to Fix P0138 Isuzu

  1. Begin by using a scan tool to verify the P0138 code and ensure it is not a false alarm.
  2. Inspect the wiring harness and connectors for any damage or corrosion. Repair or replace as needed.
  3. Test the HO2S sensor using a multimeter to check for proper voltage output. Replace the sensor if it is faulty.
  4. Clear the code from the ECM memory using the scan tool and test drive the vehicle to ensure the issue has been resolved.
  5. If the problem persists, further diagnostics may be required to identify any underlying issues with the fuel system or ECM.

Cost to Fix P0138 Isuzu

The typical repair costs for addressing a P0138 code on an Isuzu vehicle can range from $150 to $400, depending on the specific cause of the issue and the cost of parts and labor in your area. It is important to note that diagnosis time and labor rates at auto repair shops can vary, so it is advisable to check with local shops for a more accurate estimate. Keep in mind that rates at dealerships or in metropolitan areas may be higher, while independent shops may offer more competitive pricing.

Tech Notes for P0138 Isuzu

Replacing the Rear Heated Oxygen Sensor Bank 1 usually takes care of the problem.

When is the Code Detected?

The P0138 code is set when the Engine Control Module (ECM) detects that the rear O2 sensor signal voltage remains excessively high for an extended period of time.

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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.

Frequently Asked Questions about P0138 Isuzu Code

1. What does the OBDII code P0138 for Isuzu HO2S Circuit Low Voltage Sensor 2 indicate?

- This code indicates that the oxygen sensor (O2 sensor) in bank 1 sensor 2 is registering a low voltage condition.

2. What are the common symptoms of a P0138 code in an Isuzu vehicle?

- Common symptoms include poor fuel economy, rough idling, engine hesitation, and an illuminated check engine light.

3. What are the possible causes of a P0138 code in an Isuzu vehicle?

- Possible causes include a faulty oxygen sensor, damaged wiring or connectors, exhaust system leaks, and engine misfires.

4. How can I diagnose a P0138 code in my Isuzu vehicle?

- Diagnosing a P0138 code involves using an OBDII scanner to retrieve the code, inspecting the oxygen sensor and related wiring, and checking for exhaust leaks.

5. Can a P0138 code be fixed by simply replacing the oxygen sensor?

- In some cases, replacing the oxygen sensor may resolve the P0138 code. However, it's important to diagnose the issue accurately before replacing any parts.

6. Are there any repair tips for addressing a P0138 code in an Isuzu vehicle?

- Repair tips include ensuring proper installation of the oxygen sensor, checking for exhaust leaks, and verifying the integrity of the wiring harness.

7. How critical is it to address a P0138 code promptly in an Isuzu vehicle?

- While the vehicle may still be operable with a P0138 code, it's important to address it promptly to prevent potential damage to the catalytic converter and ensure optimal engine performance.

8. Can I drive my Isuzu vehicle with a P0138 code?

- It is generally safe to drive your Isuzu vehicle with a P0138 code, but it is recommended to address the issue as soon as possible to avoid further complications.

9. What is the typical cost to repair a P0138 code in an Isuzu vehicle?

- The cost of repairing a P0138 code can vary depending on the root cause of the issue, but it may range from $100 to $300 for parts and labor.

10. Is it possible to reset the check engine light after fixing a P0138 code in an Isuzu vehicle?

- Yes, the check engine light can be reset using an OBDII scanner after fixing the underlying issue causing the P0138 code.

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