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Code P0594

Symptoms

• Cruise control not engaging

• Cruise control disengages unexpectedly

• Check Engine Light illuminated

Common Causes

• Faulty cruise control servo

• Damaged or corroded wiring in the servo control circuit

• Faulty ECM

Glossary

ECM: Engine Control Module

Servo: A device used to control the speed of the vehicle in cruise control systems

Related Codes

• P0595

• P0596

Official description

Cruise Control Servo Control Circuit/Open

Laymans terms

This code means there's a problem with the part of your car that helps control the speed automatically. It's like when the remote control to your toy car stops working.

Explanation

The code P0594 is set when the Engine Control Module (ECM) detects an open circuit in the cruise control servo control circuit.

Technical description

The cruise control system uses a servo to maintain the vehicle's speed as set by the driver. The ECM monitors the servo control circuit for proper operation. If it detects an open circuit or an issue in the control circuit, it triggers the P0594 code.

Diagnosis steps

• Use an OBD-II scanner to confirm the P0594 code.

• Inspect the cruise control servo and related wiring for damage.

• Test the continuity of the servo control circuit.

Repair procedures

• Repair or replace damaged wiring in the servo control circuit.

• Replace the cruise control servo if faulty.

• Reprogram or replace the ECM if necessary.

Tools required

• OBD-II scanner

• Multimeter

• Wiring repair tools

Estimated repair cost

$100 - $500

Difficulty level

Moderate

Commonly affected vehicles

• Ford Focus

• Chevrolet Malibu

• Toyota Camry

Preventive measures

• Regularly inspect and maintain vehicle wiring.

• Ensure the cruise control system is used properly.

• Have the vehicle serviced regularly.

Error code type

Sensor Issue

User experience recommendations

• Avoid using cruise control until the issue is resolved.

• Have a professional mechanic inspect the vehicle.

Warranty information

Check with the vehicle manufacturer for warranty coverage on cruise control components.

Historical data

The P0594 code has been associated with issues in vehicles with electronic cruise control systems since the early 2000s.

Urgency level

Moderate – The vehicle can still be driven, but cruise control functionality is impaired.

Legal and safety notice

Operating a vehicle with a malfunctioning cruise control system can be hazardous. Ensure repairs are made promptly.

Testing conditions

• Vehicle must be in motion.

• Cruise control system must be engaged.

Component location

The cruise control servo is typically located near the throttle body or within the engine bay.

FAQs

Q: Can I drive my car with a P0594 code?
A: Yes, but the cruise control may not work properly. It's best to have it checked soon.

Q: Will the P0594 code affect my car's performance?
A: The main issue is with cruise control. Your car should drive normally otherwise.

Last updated: Apr 16, 2026 • Source: internal database
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