Powertrain, generic · Vehicle speed, idle control and auxiliary inputs

P0588 Cruise Control Vent Control Circuit High

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

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. P0588 means the voltage at the vent valve driver is too high – a short to positive or a valve not drawing current. The vent stays open, the servo builds no vacuum and cruise control is switched off. No manufacturer document available to us uses this code.

Likely causes

Vent control line shorted to positive
Vent valve or servo faulty
Corrosion in the connector
Engine module

Symptoms

  • 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

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–300
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

cruise control servoservo solenoid valvesservo wiringengine control module

Related codes

P0586P0587P0584P0596

References: patents.google.com, patents.google.com, law.cornell.edu.