P0596Generic code

P0596 Code: Cruise Control Servo Control Circuit High

The P0596 code means the computer sees high voltage in the cruise control servo control circuit, from an open circuit or a short to voltage. It can leave you with cruise control that does not work. Check the fuse, relay, connector and wiring before replacing anything.

Severity
Low
Can I keep driving?
Yes, no immediate risk
Estimated cost
$50 to $400
Difficulty
Medium
System
Idle and Speed Control
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

On this page

What the P0596 code means

The cruise control servo moves the throttle to hold speed. It can be vacuum operated or electric, and the computer controls it and monitors its circuit.

The computer watches the control circuit from its own driver transistor. The P0596 code means high voltage in the control circuit (an open circuit or a short to voltage). Before you replace the part, check the fuse, relay, connector and wiring, which are the most usual cause.

If the servo fails, cruise control shuts off. Check that the throttle cable is not snagged or out of adjustment.

To confirm it, measure the continuity of each wire between the component connector and the computer connector with the key off. It should be less than 1 ohm. An infinite reading means the wire is open. If the wiring is good, measure the component itself: infinite resistance confirms it is open inside.

P0596 code symptoms

  • Check engine light or another warning light on.
  • Cruise control that does not work.

Likely causes of the P0596 code

  1. Loose or broken connector. The most common cause, especially after another repair.
  2. Open coil or motor with infinite resistance.
  3. Cut control wire between the component and the computer.
  4. Short to 12 V. The control wire touches another wire that carries voltage.

How to diagnose the P0596 code step by step

  1. Activate the component with the scan tool and check whether it responds.
  2. Check the fuse and relay. Measure voltage on both sides of the fuse and swap the relay with an identical one.
  3. Measure the supply at the connector. You should see battery voltage with the key on or when you command it.
  4. Measure the component resistance and compare it with the manual, and also check the insulation to ground.
  5. Check the control wire for continuity to the computer and for the absence of shorts.

How to fix the P0596 code

  • Repair the connector, the wiring or the power supply.
  • Replace the cruise control servo if it does not respond with correct power and command.
  • Clear the codes and verify.

Technical reference data

  • Electric or vacuum servo, depending on the vehicle.
  • Reference values only: check the manufacturer data for your vehicle.

Brand-specific notes

This is uncommon on modern vehicles, where the electronic throttle does this job.

Frequently asked questions about P0596

Can I drive with the P0596 code?
Yes, with caution. The vehicle drives normally, but cruise control will not work until the servo circuit is repaired.
What does the cruise control servo do?
The cruise control servo moves the throttle to hold speed. It can be vacuum operated or electric, and the computer controls it and monitors its circuit.
Does the part always have to be replaced?
No. Check the fuses, relays, connectors and wiring first. They are the most usual cause.
How much does it cost to fix P0596?
As a guide, between $50 and $400.
What does the P0596 code mean?
The P0596 code is a generic OBD2 code for high voltage in the cruise control servo control circuit. It points to an open circuit or a short to voltage.

Related codes

Questions about the P0596 code

There are no questions about this code yet. Tell us about your case: vehicle, symptoms and what you have already checked.