AutoCodes – Ford – P1138 2003 Ford F150

P1138 2003 Ford F150 Code - Lack Of Heated Oxygen Sensor Switches Bank 1 Sensor 2 Switch Indicates Rich

Quick Answer

The Heated Oxygen Sensor 2 (HO2S2) (Downstream), after the three-way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. Common causes include Exhaust gas leaks, Faulty Heated Oxygen Sensor 2 (HO2S2) (Downstream) Bank 1, Heated Oxygen Sensor 2 Bank 1 harness is open or shorted. 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 2003 Ford F150 indicates Lack Of Heated Oxygen Sensor Switches Bank 1 Sensor 2 Switch Indicates Rich.
Common causes: Common causes include Exhaust gas leaks, Faulty Heated Oxygen Sensor 2 (HO2S2) (Downstream) Bank 1, Heated Oxygen Sensor 2 Bank 1 harness is open or shorted.
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.

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Code Popularity 2,692

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 02, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1138 2003 Ford F150 Description

The Heated Oxygen Sensor 2 (HO2S2) (Downstream), after the 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 maintain near the ideal stoichiometric ratio. The HO2S2 output voltage changes suddenly in the vicinity of the stoichiometric ratio. The Powertrain Control Module (PCM) adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric. The HO2S2 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 PCM interprets Lean when the HO2S2 voltage is below 0.45 V. If the oxygen in the exhaust gas decreases, the air-fuel ratio becomes Rich. The PCM interprets Rich when the HO2S2 voltage is above 0.45 V. The P1138 code will set when the PCM detects that the HO2S2 signal is above the voltage of range for an extended period.

OBDII Code P1138 2003 Ford F150 - Lack Of Heated Oxygen Sensor Switches Bank 1 Sensor 2 Switch Indicates Rich - AutoCodes.com — P1138 2003 Ford F150 Code - Lack Of Heated Oxygen Sensor Switches Bank 1 Sensor 2 Switch Indicates Rich

What does this mean?

What are the Possible Causes of the DTC P1138 2003 Ford F150?

Exhaust gas leaks
Faulty Heated Oxygen Sensor 2 (HO2S2) (Downstream) Bank 1
Heated Oxygen Sensor 2 Bank 1 harness is open or shorted
Heated Oxygen Sensor 2 Bank 1 circuit poor electrical connection
Inappropriate fuel pressure
Faulty fuel injectors

How to Fix the DTC P1138 2003 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1138 2003 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 P1138 2003 Ford F150 code?

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Need Help with the 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 P1138 2003 Ford F150 Code

1. What are the common symptoms of OBDII code P1138 in a 2003 Ford F150?

- Common symptoms include poor fuel economy, rough idling, and potentially a noticeable fuel smell from the exhaust.

2. What does the OBDII code P1138 "Lack Of Heated Oxygen Sensor Switches Bank 1 Sensor 2 Switch Indicates Rich" mean for a 2003 Ford F150?

- This code indicates that the heated oxygen sensor (HO2S) in Bank 1 Sensor 2 is detecting a rich air-fuel mixture, which can lead to performance issues.

3. What are the possible causes of OBDII code P1138 in a 2003 Ford F150?

- The code can be triggered by issues such as a faulty HO2S, a vacuum leak, a fuel pressure problem, or a malfunctioning engine control module (ECM).

4. How can I diagnose the OBDII code P1138 in my 2003 Ford F150?

- Diagnosing this code typically involves using a scan tool to monitor the HO2S readings, checking for vacuum leaks, testing fuel pressure, and inspecting the ECM.

5. What are some repair tips for addressing OBDII code P1138 in a 2003 Ford F150?

- Repair tips may include replacing the Bank 1 Sensor 2 HO2S, repairing any vacuum leaks, addressing fuel system issues, and potentially reprogramming or replacing the ECM.

6. Can I continue driving my 2003 Ford F150 with OBDII code P1138?

- It is not recommended to continue driving with this code, as it can lead to decreased fuel efficiency and potential engine damage if left unaddressed.

7. How much does it typically cost to repair OBDII code P1138 in a 2003 Ford F150?

- The cost of repairs can vary depending on the specific issue causing the code, but it may range from a few hundred to over a thousand dollars, including parts and labor.

8. Will resetting the OBDII code P1138 in my 2003 Ford F150 make it go away permanently?

- Resetting the code may temporarily turn off the check engine light, but if the underlying issue is not fixed, the code is likely to return after a certain number of drive cycles.

9. Can a DIY enthusiast fix OBDII code P1138 in a 2003 Ford F150?

- While some aspects of diagnosing and repairing this code may be tackled by a skilled DIYer, certain tasks like replacing the HO2S or addressing ECM issues may require professional expertise.

10. How often should I get my 2003 Ford F150's emissions system checked to prevent OBDII code P1138?

- It is recommended to have your vehicle's emissions system checked during regular maintenance intervals to catch potential issues early and prevent codes like P1138 from occurring.