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Engine-Codes – Ford – P0138 1998 Ford F150

P0138 1998 Ford F150 Code - O2 Sensor Circuit High Voltage Bank 1 Sensor 2

Quick Answer

The P0138 diagnostic trouble code (DTC) for a 1998 Ford F150 indicates an issue with the O2 sensor circuit having high voltage in Bank 1 Sensor 2. Common causes include Faulty O2 sensor, Wiring or connector issues in the O2 sensor circuit, Exhaust leaks near the O2 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 1998 Ford F150 indicates O2 Sensor Circuit High Voltage Bank 1 Sensor 2.
Common causes
Common causes include Faulty O2 sensor, Wiring or connector issues in the O2 sensor circuit, Exhaust leaks near the O2 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.
What is this?
Table of contents Created and updated by William Orellana on Sep 14, 2024
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Code P0138 1998 Ford F150 Description

The P0138 diagnostic trouble code (DTC) for a 1998 Ford F150 indicates an issue with the O2 sensor circuit having high voltage in Bank 1 Sensor 2. The O2 sensor, also known as the oxygen sensor, plays a crucial role in monitoring the oxygen levels in the exhaust gases. Bank 1 Sensor 2 refers to the sensor located downstream of the catalytic converter on the side of the engine where cylinder 1 is located.

OBDII Code P0138 1998 Ford F150 - O2 Sensor Circuit High Voltage Bank 1 Sensor 2
P0138 1998 Ford F150 Code - O2 Sensor Circuit High Voltage Bank 1 Sensor 2

Common Causes of P0138 1998 Ford F150

  1. Faulty O2 sensor
  2. Wiring or connector issues in the O2 sensor circuit
  3. Exhaust leaks near the O2 sensor
  4. ECM malfunction
  5. Contaminated fuel affecting sensor readings

Symptoms of P0138 1998 Ford F150

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

How to Fix P0138 1998 Ford F150

  1. Use an OBD-II scanner to confirm the P0138 code and pinpoint the exact cause.
  2. Inspect the wiring and connectors in the O2 sensor circuit for any damage or corrosion.
  3. Test the O2 sensor using a multimeter to check for proper voltage output.
  4. Replace the O2 sensor if it is found to be faulty.
  5. Clear the DTC and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0138 1998 Ford F150

The cost of repairing a P0138 code on a 1998 Ford F150 can vary depending on the specific cause of the issue. In general, the cost of a new O2 sensor can range from $50 to $200, depending on the brand and quality. Labor costs for the repair can range from $100 to $300, depending on the shop's hourly rate and the complexity of the repair. Overall, the total repair cost for addressing a P0138 code can range from $150 to $500. It's recommended to consult with a trusted mechanic or auto repair shop to get an accurate estimate based on your specific vehicle and location.

What does this mean?

Tech Notes for P0138 1998 Ford F150

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

The HO2S Sensor Signals are monitored for an over voltage fault. The code is set when HO2S signal voltage is 1.5 volts or greater.

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 1998 Ford F150 Code

1. What are the common symptoms of OBDII code P0138 in a 1998 Ford F150?

- Common symptoms include poor fuel economy, rough idling, engine stalling, and the illumination of the Check Engine Light.

2. What does the OBDII code P0138 on a 1998 Ford F150 indicate?

- The code P0138 indicates a high voltage condition in the O2 sensor circuit of Bank 1 Sensor 2 in the exhaust system.

3. What are the possible causes of OBDII code P0138 in a 1998 Ford F150?

- Possible causes include a faulty O2 sensor, wiring issues, exhaust leaks, engine misfires, or a malfunctioning PCM (Powertrain Control Module).

4. How can I diagnose and repair OBDII code P0138 on my 1998 Ford F150?

- Start by inspecting the O2 sensor wiring for any damage or corrosion. Check for exhaust leaks and ensure proper sensor operation. If necessary, replace the O2 sensor or repair the wiring connections.

5. Can a dirty or contaminated O2 sensor trigger code P0138 on a 1998 Ford F150?

- Yes, a dirty or contaminated O2 sensor can cause erratic readings and trigger a high voltage condition, leading to the activation of code P0138.

6. Is it safe to continue driving my 1998 Ford F150 with OBDII code P0138 present?

- It is not recommended to drive with code P0138 present, as it can lead to decreased fuel efficiency, engine performance issues, and potential damage to the catalytic converter over time.

7. How do I reset the Check Engine Light after repairing OBDII code P0138 on my 1998 Ford F150?

- You can reset the Check Engine Light using an OBDII scanner. Once the repair is completed, clear the trouble codes and monitor the system for any recurrence of the issue.

8. Will replacing the O2 sensor fix OBDII code P0138 in a 1998 Ford F150?

- In many cases, replacing a faulty O2 sensor can resolve code P0138. However, it is essential to ensure proper diagnosis and address any underlying wiring or exhaust issues.

9. How long does it take to repair OBDII code P0138 on a 1998 Ford F150?

- The repair time for code P0138 can vary depending on the exact cause and the complexity of the repair. It may take anywhere from 30 minutes to a few hours to complete the repair.

10. Can a DIY enthusiast tackle the repair of OBDII code P0138 on a 1998 Ford F150?

- Yes, with the right tools and knowledge, a DIY enthusiast can diagnose and repair code P0138. However, if unsure, it is recommended to seek professional help to ensure the issue is resolved correctly.

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