P0594 OBD II Trouble Code Cruise Control Servo Control Circuit /Open

How to quickly diagnose, repair, and causes of a P0594 trouble code which indicates a detected open condition or general malfunction in the cruise control servo control circuit.

Symptoms of P0594 OBD II Trouble Code

  • Cruise control inoperative
  • Erratic cruise control operation
  • Vehicle speed stuck
  • Vehicle speed limited with cruise control active
  • Inaccurate vehicle speed setting when compared to desired or set speed
  • Specific cruise control(s) functions malfunctioning/erratic

Common Causes of P0594 OBD II Trouble Code

  • Defective/damaged cruise control servo
  • Cruise control servo cable broken/stuck/disconnected/mis-adjusted
  • Wiring issue
  • ECM (engine control module) issue
  • Module water intrusion
  • Connector issue

Severity of P0594 OBD II Trouble Code

I am going to set the severity for this code to medium. As far as most cruise control OBD2 fault codes go, they are fairly minor. That being said, in this case, because the cruise control servo is not only directly connected to the throttle control via cable but is responsible for throttle position at times, it would be more severe than most.