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P0138 2002 Ford F150 Code - O2 Sensor Circuit High Voltage Bank 1 Sensor 2

Quick Answer

The O2 sensor, or oxygen sensor, in a vehicle plays a crucial role in monitoring the oxygen levels in the exhaust gases to ensure proper fuel mixture and emissions control. Common causes include Faulty O2 sensor, Wiring or connector issues in the O2 sensor circuit, Exhaust leaks near the 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 2002 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 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 11, 2024
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Code P0138 2002 Ford F150 Description

The O2 sensor, or oxygen sensor, in a vehicle plays a crucial role in monitoring the oxygen levels in the exhaust gases to ensure proper fuel mixture and emissions control. The P0138 diagnostic trouble code (DTC) specifically refers to an issue with the O2 sensor circuit in Bank 1 Sensor 2, indicating that the signal being received by the engine control module (ECM) from this sensor is showing a high voltage reading. This can lead to a variety of performance issues and potentially harmful effects on the vehicle if left unaddressed.

OBDII Code P0138 2002 Ford F150 - O2 Sensor Circuit High Voltage Bank 1 Sensor 2
P0138 2002 Ford F150 Code - O2 Sensor Circuit High Voltage Bank 1 Sensor 2

Common Causes of P0138 2002 Ford F150

  1. Faulty O2 sensor
  2. Wiring or connector issues in the O2 sensor circuit
  3. Exhaust leaks near the sensor
  4. Engine running rich due to issues with fuel injectors or fuel pressure
  5. Malfunctioning ECM

Symptoms of P0138 2002 Ford F150

  1. Decreased fuel efficiency
  2. Rough idle or stalling
  3. Increased emissions
  4. Check Engine Light illuminated
  5. Loss of engine power

How to Fix P0138 2002 Ford F150

  1. Begin by performing a visual inspection of the O2 sensor and its wiring to check for any obvious signs of damage or corrosion.
  2. Use a multimeter to test the O2 sensor's voltage output and compare it to the manufacturer's specifications to determine if it is functioning correctly.
  3. If the O2 sensor is faulty, replace it with a new sensor that meets the OEM specifications for the vehicle.
  4. Check and repair any damaged wiring or connectors in the O2 sensor circuit.
  5. Clear the DTC using a scan tool and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0138 2002 Ford F150

The cost of repairing a P0138 DTC in a 2002 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 add an additional $100 to $200, depending on the shop's hourly rate and the complexity of the repair. Overall, the total repair cost for this issue can range from $150 to $400. It's important to note that these are rough estimates, and actual costs may vary based on individual circumstances and location.

What does this mean?

Tech Notes for P0138 2002 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 2002 Ford F150 Code

1. What are the common symptoms of OBDII code P0138 on a 2002 Ford F150?

- Common symptoms include poor fuel economy, rough idling, engine hesitation, and potential loss of power.

2. What does the OBDII code P0138 indicate on a 2002 Ford F150?

- The code P0138 specifically points to an issue with the O2 sensor circuit high voltage for Bank 1 Sensor 2 in the vehicle's exhaust system.

3. What are the possible causes of the O2 sensor circuit high voltage fault on Bank 1 Sensor 2 in a 2002 Ford F150?

- Common causes include a faulty O2 sensor, damaged wiring or connectors, exhaust leaks, or issues with the vehicle's engine control module (ECM).

4. How can I diagnose the O2 sensor circuit high voltage issue on Bank 1 Sensor 2 in my 2002 Ford F150?

- Use a scan tool to read and clear the trouble code, inspect the O2 sensor and its wiring for any damage, and check for exhaust leaks near the sensor.

5. Can I continue driving my 2002 Ford F150 with the P0138 code?

- It is not recommended to continue driving with the P0138 code as it can lead to decreased fuel efficiency and potential damage to the catalytic converter.

6. How do I repair the O2 sensor circuit high voltage fault on Bank 1 Sensor 2 in my 2002 Ford F150?

- Repair options include replacing the faulty O2 sensor, repairing damaged wiring or connectors, fixing any exhaust leaks, or resetting the ECM.

7. Is it possible to reset the OBDII code P0138 on a 2002 Ford F150 without fixing the underlying issue?

- While you can clear the code using a scan tool, it is essential to address the root cause of the problem to prevent it from reoccurring.

8. Can a dirty air filter cause the O2 sensor circuit high voltage fault on a 2002 Ford F150?

- A dirty air filter is unlikely to directly cause the P0138 code, but it can impact overall engine performance and fuel efficiency, so it's still important to maintain a clean air filter.

9. How much does it cost to replace an O2 sensor on a 2002 Ford F150?

- The cost of replacing an O2 sensor can vary depending on the brand, location, and whether you choose to do it yourself or have a professional mechanic perform the replacement.

10. Will driving at high speeds affect the O2 sensor circuit high voltage fault on a 2002 Ford F150?

- Driving at high speeds may not directly affect the O2 sensor circuit fault, but it's important to address the issue promptly to prevent any further damage to the vehicle's systems.

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