AutoCodes – Ford – P1138 1999 Ford F150

P1138 1999 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 1999 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 3,242

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 Jul 24, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1138 1999 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 1999 Ford F150 - Lack Of Heated Oxygen Sensor Switches Bank 1 Sensor 2 Switch Indicates Rich - AutoCodes.com — P1138 1999 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 1999 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 1999 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 1999 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 1999 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 P1138 1999 Ford F150 Code

1. What are the common symptoms of OBDII code P1138 on a 1999 Ford F150?

- The common symptoms include decreased fuel efficiency, rough idling, and possibly a noticeable smell of unburned fuel.

2. What are the possible causes of OBDII code P1138 on a 1999 Ford F150?

- The code P1138 typically indicates a problem with the Bank 1 Sensor 2 oxygen sensor, which could be caused by a faulty sensor, wiring issues, or a rich fuel mixture.

3. How can I diagnose the issue causing OBDII code P1138 on my 1999 Ford F150?

- Using an OBDII scanner to read the code and then inspecting the Bank 1 Sensor 2 oxygen sensor and its wiring can help diagnose the issue.

4. Can a dirty or clogged air filter trigger OBDII code P1138 on a 1999 Ford F150?

- Yes, a dirty or clogged air filter can lead to a rich fuel mixture, which may trigger the code P1138. It's recommended to check and replace the air filter if necessary.

5. What is the significance of the Bank 1 Sensor 2 oxygen sensor in relation to OBDII code P1138 on a 1999 Ford F150?

- The Bank 1 Sensor 2 oxygen sensor monitors the exhaust after the catalytic converter and plays a crucial role in adjusting the fuel mixture. A malfunction in this sensor can trigger the code P1138.

6. How can I repair OBDII code P1138 on my 1999 Ford F150?

- Repairing the issue may involve replacing the Bank 1 Sensor 2 oxygen sensor if it's faulty, checking and repairing any damaged wiring, and ensuring the fuel mixture is within the correct range.

7. Can driving with OBDII code P1138 on a 1999 Ford F150 cause further damage to the vehicle?

- Continuing to drive with the code P1138 may lead to reduced fuel efficiency and performance, as well as potential damage to the catalytic converter over time.

8. Are there any DIY tips for addressing OBDII code P1138 on a 1999 Ford F150?

- DIY tips include checking for loose or damaged wiring connected to the Bank 1 Sensor 2 oxygen sensor, ensuring the sensor is securely in place, and clearing the code to see if it returns.

9. Is it safe to ignore OBDII code P1138 on a 1999 Ford F150?

- Ignoring the code P1138 can lead to decreased fuel efficiency and potential damage to the vehicle's emissions system. It's recommended to address the issue promptly.

10. How much does it typically cost to repair OBDII code P1138 on a 1999 Ford F150?

- The cost of repairing the code P1138 can vary depending on the underlying issue, but it may involve replacing the oxygen sensor, which can range from $100 to $300 including parts and labor.