Damaged, chafed or corroded wiring to the servo control circuit (short to ground or high resistance); Poor connection or corroded terminals at the servo or control unit connector; Faulty cruise control servo or actuator with an internal short or open circuit; Blown fuse or a fault in the power or earth supply to the servo; Faulty brake or clutch pedal switch affecting cruise control circuit logic (varies by model); Fault inside the cruise control module or engine control unit; Water ingress into the servo or its connector.

P0595

Cruise Control Servo Control Circuit Low.

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
95: FaultThe specific fault in that area

What it means

P0595 is the generic SAE J2012 code for a Cruise Control Servo Control Circuit Low fault. The control unit that manages the cruise control servo (or vacuum/electric actuator that moves the throttle linkage) saw a voltage lower than expected on the servo control circuit. The cruise control is normally disabled while the fault is present. Servo design varies between vehicles, and many modern cars use electronic throttle control instead, so the exact hardware depends on the model.

Symptoms

Cruise control will not engage or cuts out unexpectedly
Cruise control warning or fault light on the dash
Malfunction indicator lamp may be on
Cruise set speed not held or the speed surges
Brake light or brake switch related faults stored alongside it

Possible causes

Damaged, chafed or corroded wiring to the servo control circuit (short to ground or high resistance)likely
Poor connection or corroded terminals at the servo or control unit connectorlikely
Faulty cruise control servo or actuator with an internal short or open circuitlikely
Blown fuse or a fault in the power or earth supply to the servopossible
Faulty brake or clutch pedal switch affecting cruise control circuit logic (varies by model)possible
Fault inside the cruise control module or engine control unitrare
Water ingress into the servo or its connectorrare

How to diagnose

Read all stored codes and freeze frame data, noting any other cruise, brake switch or throttle codes
Check the relevant fuses and look up the cruise control circuit in the wiring diagram for your model
Visually inspect the servo, its vacuum lines if fitted, and the wiring and connectors for damage, chafing, moisture or corrosion
Check the brake and clutch pedal switches for correct operation and adjustment
Measure the supply voltage and earth at the servo connector with the ignition on
Check the servo control wire for a short to ground and for continuity back to the control unit with the connectors unplugged
Test the servo resistance or operation against the manufacturer's specification
Clear the code and road test, checking whether it returns and under what conditions

How to fix

Repair or replace damaged wiring and terminals in the servo control circuit
Clean, secure or replace corroded or loose connectors
Replace the cruise control servo or actuator if it is faulty
Replace the blown fuse after finding and fixing the cause of the overload
Replace or adjust a faulty brake or clutch pedal switch
Repair or replace the control unit only after the wiring and servo have been proven good

Can I keep driving?

Low severity

The car can normally be driven as usual, but the cruise control will probably not work. Book it in for repair at your convenience.

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