Cruise Control Servo Control Circuit/Open
What it means
P0594 means the module detected an open circuit in the cruise control servo control — the actuator that adjusts throttle to hold your set speed. It's a comfort-feature fault: cruise control won't engage or hold speed, but the engine and drivability are unaffected. The usual causes are broken wiring, a bad connector, or a failed servo.
Can I keep driving? Safe to drive — only the cruise control is affected; the engine runs and drives normally.
Real-world scan data
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Cruise control won't engage or won't hold a set speed
- Cruise indicator light may not come on
- Check-engine light on
Common causes
Most likely first
- Open circuit in the cruise control servo wiringLikely
- Failed cruise control servo/actuatorCommon
- Corroded or disconnected connector at the servoCommon
- Faulty cruise control switch or moduleLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame, then check the servo control circuit for an open — inspect the connector and back-probe for continuity.
- Measure the servo winding resistance and compare to spec; an open winding confirms a failed servo.
- Repair broken wiring or corroded pins in the servo circuit.
- Replace the servo if it's internally open. Clear and re-test cruise operation.
FAQ
Quick answers
Is it safe to drive with P0594?+
Can I just clear P0594?+
Related codes
Read & clear P0594 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.