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Engine-Codes – Generic – P0591

P0591 Code - Speed Control Multiplexed Switch Performance

Quick Answer

The OBD-II code P0591 indicates a problem with the speed control multiplexed switch performance in the vehicle. Common causes include Faulty speed control multiplexed switch, Damaged wiring or connectors, Corrosion in the switch or wiring. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means
P0591 indicates Speed Control Multiplexed Switch Performance.
Common causes
Common causes include Faulty speed control multiplexed switch, Damaged wiring or connectors, Corrosion in the switch or wiring.
Severity
Low - monitor the vehicle and repair when practical.
Can I drive?
The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.
What is this?
Table of contents Created and updated by William Orellana on Sep 17, 2024
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Code P0591 Description

The OBD-II code P0591 indicates a problem with the speed control multiplexed switch performance in the vehicle. This code is typically found in vehicles equipped with electronic throttle control systems. The speed control multiplexed switch is responsible for sending signals to the engine control module (ECM) to adjust the throttle position based on the driver's input. When this switch malfunctions or fails to perform as expected, it can lead to issues with the vehicle's speed control system.

OBDII Code P0591 - Speed Control Multiplexed Switch Performance
P0591 Code - Speed Control Multiplexed Switch Performance

Common Causes of P0591

  1. Faulty speed control multiplexed switch
  2. Damaged wiring or connectors
  3. Corrosion in the switch or wiring
  4. ECM software issues
  5. Electrical system problems

Symptoms of P0591

  1. Cruise control not working or unable to set a constant speed
  2. Erratic throttle response
  3. Poor acceleration or deceleration
  4. Vehicle going into limp mode

How to Fix P0591

  1. Use a scan tool to retrieve the trouble code and confirm the issue.
  2. Inspect the speed control multiplexed switch and its wiring for any visible damage or corrosion.
  3. Test the switch's functionality using a multimeter to check for proper voltage and continuity.
  4. If the switch is faulty, replace it with a new one.
  5. Clear the trouble code and test the vehicle to ensure the issue has been resolved.

Cost to Fix P0591

The cost of repairing a P0591 code can vary depending on the make and model of the vehicle, as well as the labor rates in your area. On average, replacing a speed control multiplexed switch can cost between $150 and $300, including parts and labor. It's important to note that diagnostic time and labor rates at auto repair shops can vary, so it's best to check with local shops for a more accurate estimate.

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Code P0591 Information for Specific Makes

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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