AutoCodes – Ford – P1138 2001 Ford F150

P1138 2001 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 2001 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 3,096

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 2001 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 2001 Ford F150 - Lack Of Heated Oxygen Sensor Switches Bank 1 Sensor 2 Switch Indicates Rich - AutoCodes.com — P1138 2001 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 2001 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 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1138 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 P1138 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 P1138 2001 Ford F150 Code

1. What does the OBDII code P1138 mean on a 2001 Ford F150?

P1138 indicates that the heated oxygen sensor (Bank 1, Sensor 2) is not switching properly and is detecting a consistently rich condition in the exhaust stream.

2. What are common symptoms of code P1138 in a Ford F150?

Symptoms may include reduced fuel efficiency, rough idling, black smoke from the exhaust, poor engine performance, and an illuminated check engine light.

3. What causes the P1138 code on a 2001 Ford F150?

Common causes include a faulty downstream oxygen sensor, wiring or connector issues, a rich-running engine due to a fuel system problem, or exhaust leaks near the sensor.

4. How do I diagnose the P1138 code on my Ford F150?

Start by inspecting the Bank 1 Sensor 2 wiring and connectors for damage. Check for exhaust leaks, ensure the sensor is functioning correctly, and verify proper fuel system operation using a scan tool.

5. What is Bank 1 Sensor 2 on a 2001 Ford F150?

Bank 1 refers to the side of the engine with cylinder #1, and Sensor 2 is the downstream oxygen sensor located after the catalytic converter on that side.

6. Can a bad oxygen sensor cause code P1138?

Yes, a malfunctioning downstream oxygen sensor (Bank 1, Sensor 2) is a common cause of this code, as it may fail to provide accurate readings.

7. How do I fix the P1138 code on a Ford F150?

Repair steps may include replacing the faulty oxygen sensor, fixing any damaged wiring or connectors, addressing exhaust leaks, and resolving any rich-running engine issues.

8. Can I drive with the P1138 code on my Ford F150?

Driving with this code is possible but not recommended, as a rich condition can damage the catalytic converter and reduce fuel efficiency over time.

9. How much does it cost to fix the P1138 code on a Ford F150?

Repairs can range from $100 to $300, depending on whether the oxygen sensor needs replacement or if additional repairs, such as fixing exhaust leaks, are required.

10. Does clearing the P1138 code fix the problem?

Clearing the code will turn off the check engine light temporarily, but the code will return if the underlying issue is not resolved.