Engine-CodesGeneric – P0596

P0596 Code - Speed Control Servo Control Circuit High

Quick Answer

The P0596 diagnostic trouble code (DTC) refers to a Speed Control Servo Control Circuit High. Common causes include Faulty speed control servo: A defective speed control servo can cause the circuit to operate at a higher voltage than normal, Damaged wiring: Corroded or damaged wiring in the speed control servo control circuit can lead to a high voltage condition, ECM malfunction: A malfunctioning Engine Control Module (ECM) can send incorrect signals to the speed control servo, causing voltage irregularities. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means
P0596 indicates Speed Control Servo Control Circuit High.
Common causes
Common causes include Faulty speed control servo: A defective speed control servo can cause the circuit to operate at a higher voltage than normal, Damaged wiring: Corroded or damaged wiring in the speed control servo control circuit can lead to a high voltage condition, ECM malfunction: A malfunctioning Engine Control Module (ECM) can send incorrect signals to the speed control servo, causing voltage irregularities.
Severity
Moderate - service should be scheduled soon.
Can I drive?
The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
Table of contents Created and updated by William Orellana on Sep 19, 2024
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Code P0596 Description

The P0596 diagnostic trouble code (DTC) refers to a Speed Control Servo Control Circuit High. This code indicates that there is a high voltage condition in the speed control servo control circuit. The speed control servo is responsible for maintaining a constant speed of the vehicle, often referred to as cruise control. When this circuit is compromised, it can lead to issues with the vehicle's speed control system.

OBDII Code P0596 - Speed Control Servo Control Circuit High
P0596 Code - Speed Control Servo Control Circuit High

Common Causes of P0596

  1. Faulty speed control servo: A defective speed control servo can cause the circuit to operate at a higher voltage than normal.
  2. Damaged wiring: Corroded or damaged wiring in the speed control servo control circuit can lead to a high voltage condition.
  3. ECM malfunction: A malfunctioning Engine Control Module (ECM) can send incorrect signals to the speed control servo, causing voltage irregularities.
  4. Short circuit: A short circuit in the speed control servo control circuit can result in a high voltage condition.

Symptoms of P0596

  1. Inoperative cruise control: One of the most common symptoms associated with the P0596 code is the inability to engage or maintain cruise control.
  2. Speed fluctuations: The vehicle may experience sudden changes in speed while the cruise control is engaged.
  3. Check Engine Light: The illumination of the Check Engine Light on the dashboard is a common indicator of this code being present.
  4. Reduced fuel efficiency: A malfunctioning speed control servo control circuit can lead to decreased fuel efficiency due to inconsistent speed control.

How to Fix P0596

  1. Diagnose the issue: Use a diagnostic scanner to retrieve the trouble codes and pinpoint the exact cause of the high voltage condition in the speed control servo control circuit.
  2. Inspect wiring: Thoroughly inspect the wiring harness connected to the speed control servo for any signs of damage or corrosion. Repair or replace any damaged wiring.
  3. Test speed control servo: Test the speed control servo to determine if it is functioning properly. Replace the servo if it is found to be faulty.
  4. Check ECM: Inspect the Engine Control Module (ECM) for any signs of malfunction. If necessary, reprogram or replace the ECM to address the high voltage condition.
  5. Clear codes and test: After completing the repairs, clear the trouble codes from the ECM and test the vehicle to ensure that the issue has been resolved.

Cost to Fix P0596

The cost of repairing a P0596 code can vary depending on the specific cause of the issue and the make and model of the vehicle. In general, the cost of parts for this repair can range from $100 to $300, with labor costs adding an additional $100 to $200. Overall, the total repair cost for addressing a Speed Control Servo Control Circuit High issue typically falls between $200 and $500. It's important to note that diagnostic time and labor rates at auto repair shops can vary, so it's recommended to obtain quotes from local shops for a more accurate estimate.

When is the Code Detected?

Open or shorted condition in the cruise control servo circuit

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Code P0596 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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