Engine-CodesMercury – P1138 Mercury

P1138 Mercury Code - Lack Of Heated Oxygen Sensor Switches Bank 1 Sensor 2 Switch Indicates Rich

Quick Answer

The diagnostic trouble code P1138 for Mercury vehicles indicates a lack of heated oxygen sensor switches on Bank 1 Sensor 2, with the switch indicating a rich fuel mixture. Common causes include Faulty oxygen sensor, Wiring or connector issues, Vacuum leaks. 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 Mercury indicates Lack Of Heated Oxygen Sensor Switches Bank 1 Sensor 2 Switch Indicates Rich.
Common causes
Common causes include Faulty oxygen sensor, Wiring or connector issues, Vacuum leaks.
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.
Table of contents Created and updated by William Orellana on Sep 10, 2024
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Code P1138 Mercury Description

The diagnostic trouble code P1138 for Mercury vehicles indicates a lack of heated oxygen sensor switches on Bank 1 Sensor 2, with the switch indicating a rich fuel mixture. This code typically points to an issue with the oxygen sensor located downstream from the catalytic converter on the bank 1 side of the engine.

OBDII Code P1138 Mercury - Lack Of Heated Oxygen Sensor Switches Bank 1 Sensor 2 Switch Indicates Rich
P1138 Mercury Code - Lack Of Heated Oxygen Sensor Switches Bank 1 Sensor 2 Switch Indicates Rich

Common Causes of P1138 Mercury

  1. Faulty oxygen sensor
  2. Wiring or connector issues
  3. Vacuum leaks
  4. Fuel pressure regulator malfunction
  5. Exhaust system leaks

Symptoms of P1138 Mercury

  1. Decreased fuel efficiency
  2. Rough idling or stalling
  3. Check Engine Light illuminated
  4. Strong fuel odor from the exhaust
  5. Failed emissions test

How to Fix P1138 Mercury

  1. Perform a diagnostic scan to confirm the P1138 code and identify the specific issue.
  2. Inspect the oxygen sensor for any signs of damage or contamination and replace if necessary.
  3. Check the wiring and connectors for any breaks or corrosion and repair as needed.
  4. Test the fuel pressure regulator and vacuum system for proper operation.
  5. Inspect the exhaust system for leaks and repair or replace any damaged components.

Cost to Fix P1138 Mercury

The cost of repairing a P1138 code on a Mercury vehicle can vary depending on the specific cause of the issue. Typically, the cost of replacing an oxygen sensor ranges from $100 to $250, including parts and labor. Additional costs may apply if other components need to be repaired or replaced. It's important to note that diagnostic time and labor rates at auto repair shops can influence the final cost, so it's recommended to obtain a detailed estimate from a qualified mechanic.

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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.

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