P0596Cruise Control Servo Control Circuit High
- Generic OBD-II code · Powertrain
- How the car detects it
- Older engines without electronic throttle use a vacuum cruise servo on the throttle cable: a vacuum valve (closed when unpowered) opens the throttle with intake vacuum, a vent valve (open when unpowered) holds or releases it, and a dump valve fed through the brake switch vents it when braking. Where the engine module drives these valves, it checks each circuit and switches cruise off; CARB treats this as emission-neutral, usually without warning lamp. P0596 means the voltage in the servo supply or control circuit is too high, for example a short to positive keeping supply on while braking – safety-relevant, because the brake switch cut-off could then fail; cruise control is locked out. No manufacturer document available to us uses this code.
- What you may notice
- Cruise control cannot be engaged or switches off
- Cruise indicator goes out or flashes (depending on vehicle)
- Usually no check engine light, code stored only
- Likely causes
- LikelyServo supply line shorted to positive
- PossibleBrake light switch sticking
- PossibleServo faulty
- RareEngine module
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.