Faulty cruise control vent solenoid or valve (internal short or open coil); Damaged wiring or chafed loom causing a short to voltage on the vent control circuit; Corroded, loose or contaminated connector at the vent valve or control unit; Open circuit in the vent control wiring or poor earth on the vent device; Faulty brake switch or cruise control module affecting the vent circuit operation (varies by model); Fault inside the engine control unit driver circuit.

P0588

Cruise Control Vent Control Circuit High.

Generic
Powertrain
Generic code
Low severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
5: AreaVehicle speed, idle control and auxiliary inputs
88: FaultThe specific fault in that area

What it means

P0588 means the engine control unit has detected a high voltage or signal on the cruise control vent control circuit. The vent solenoid or valve releases vacuum in the cruise control actuator system. The control unit saw a circuit voltage higher than expected for the commanded state, which points to a short to voltage, an open circuit or a faulty vent device. Whether this code applies depends on the vehicle, as many modern cars use electronic throttle and have no vacuum-operated cruise control.

Symptoms

Cruise control will not engage or drops out unexpectedly
Cruise control cannot hold a steady speed
Malfunction indicator lamp or cruise control warning light on
Cruise control surges or releases abruptly when the brake is pressed
No other noticeable driveability change in many cases

Possible causes

Faulty cruise control vent solenoid or valve (internal short or open coil)likely
Damaged wiring or chafed loom causing a short to voltage on the vent control circuitlikely
Corroded, loose or contaminated connector at the vent valve or control unitpossible
Open circuit in the vent control wiring or poor earth on the vent devicepossible
Faulty brake switch or cruise control module affecting the vent circuit operation (varies by model)possible
Fault inside the engine control unit driver circuitrare

How to diagnose

Read all stored and pending codes and note the freeze frame data, then check for related brake switch or cruise control codes
Check the cruise control operation and note when it fails to engage or cancels
Visually inspect the vent valve, its vacuum hoses and the wiring loom for damage, chafing, heat damage or water ingress
Disconnect and inspect the connectors at the vent valve and control unit for corrosion, bent pins or poor tension
Measure the vent valve coil resistance and compare it with the manufacturer specification for that model
With the ignition on, check the supply voltage and earth at the valve connector, and test the control wire for a short to voltage using a wiring diagram
Check the brake switch signal and the cruise control switch inputs, as the vent circuit may depend on them
Clear the code and road test to see if it returns, confirming the repair

How to fix

Replace the cruise control vent solenoid or valve if its resistance or operation is out of specification
Repair or replace damaged wiring, correcting any short to voltage or open circuit
Clean, repair or replace corroded or loose connectors and terminals
Restore a good earth connection where the circuit relies on one
Replace a faulty brake switch if it is found to be disrupting the circuit
Repair or replace the control unit only after the wiring and vent device have been proven good

Can I keep driving?

Low severity

The car is normally safe to drive, as the fault mainly affects cruise control. Book it in for diagnosis, and avoid relying on cruise control until it is repaired.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.