AutoCodes – Ford – P0138 2001 Ford F150

P0138 2001 Ford F150 Code - O2 Sensor Circuit High Voltage Bank 1 Sensor 2

Quick Answer

The Heated Oxygen Sensor 2 (HO2S) (Rear O2 Sensor), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. Common causes include Faulty Rear Heated Oxygen Sensor Bank 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection. 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 2001 Ford F150 indicates O2 Sensor Circuit High Voltage Bank 1 Sensor 2.
Common causes: Common causes include Faulty Rear Heated Oxygen Sensor Bank 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection.
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 Popularity 2,983

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 14, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0138 2001 Ford F150 Description

The Heated Oxygen Sensor 2 (HO2S) (Rear O2 Sensor), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. For optimum catalyst operation, the air fuel mixture (air-fuel ratio) must be maintained near the ideal stoichiometric ratio. The HO2S output voltage changes suddenly in the vicinity of the stoichiometric ratio. The Engine Control Module (ECM) adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric. The HO2S generates a voltage between 0.1 and 0.9 V in response to oxygen in the exhaust gas. If the oxygen in the exhaust gas increases, the air-fuel ratio becomes Lean. The ECM interprets Lean when the HO2S voltage is below 0.45 V. If the oxygen in the exhaust gas decreases, the air-fuel ratio becomes Rich. The ECM interprets Rich when the HO2S voltage is above 0.45 V.

OBDII Code P0138 2001 Ford F150 - O2 Sensor Circuit High Voltage Bank 1 Sensor 2 - AutoCodes.com — P0138 2001 Ford F150 Code - O2 Sensor Circuit High Voltage Bank 1 Sensor 2

What does this mean?

What are the Possible Causes of the DTC P0138 2001 Ford F150?

Faulty Rear Heated Oxygen Sensor Bank 1
Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
Intake air leaks
Exhaust gas leaks
Inappropriate fuel pressure
Faulty fuel injectors

How to Fix the DTC P0138 2001 Ford F150?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

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.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0138 2001 Ford F150 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0138 2001 Ford F150 code?

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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 2001 Ford F150 Code

1. What are the common symptoms of OBDII code P0138 on a 2001 Ford F150?

- Common symptoms include decreased fuel efficiency, rough idling, engine misfires, and the illumination of the Check Engine light.

2. What does the OBDII code P0138 for a 2001 Ford F150 mean?

- The code indicates a high voltage condition in the O2 sensor circuit for Bank 1 Sensor 2, which is the downstream sensor on the same side as the #1 cylinder.

3. What are the possible causes of O2 sensor circuit high voltage in Bank 1 Sensor 2 on a 2001 Ford F150?

- Common causes include a faulty O2 sensor, damaged wiring or connectors, exhaust leaks near the sensor, or issues with the engine's air-fuel mixture.

4. How can I diagnose and repair OBDII code P0138 on my 2001 Ford F150?

- Start by inspecting the O2 sensor wiring and connections for any damage. Test the sensor's voltage output and replace it if necessary. Check for exhaust leaks and address any issues with the air-fuel mixture.

5. Can driving with OBDII code P0138 on a 2001 Ford F150 cause further damage?

- While driving with this code may not immediately harm the vehicle, it can lead to decreased fuel efficiency and potential damage to the catalytic converter over time if left unresolved.

6. Do I need special tools to fix O2 sensor circuit high voltage in Bank 1 Sensor 2 on my 2001 Ford F150?

- Basic tools such as a multimeter, O2 sensor socket, and a vehicle jack may be required to diagnose and repair this issue. Specialized tools may be needed for more advanced troubleshooting.

7. Can I reset the Check Engine light after fixing OBDII code P0138 on my 2001 Ford F150?

- Yes, you can reset the Check Engine light using an OBDII scanner or by disconnecting the car's battery for a few minutes. However, it is recommended to confirm that the issue has been resolved before resetting the light.

8. How can I prevent O2 sensor circuit high voltage issues in the future on my 2001 Ford F150?

- Regular maintenance, such as checking and replacing O2 sensors according to the manufacturer's recommended intervals, keeping the engine properly tuned, and addressing any exhaust leaks promptly, can help prevent such issues.

9. Is it safe to continue driving my 2001 Ford F150 with OBDII code P0138 without immediate repair?

- While the vehicle may still be operable with this code, continued driving without addressing the underlying issue can lead to decreased performance and potential long-term damage to the engine and emissions system.

10. How much does it typically cost to repair O2 sensor circuit high voltage in Bank 1 Sensor 2 on a 2001 Ford F150?

- The cost of repairs can vary depending on the exact cause of the issue, but typically, replacing an O2 sensor can range from $100 to $300, while addressing wiring or other issues may require additional labor costs.