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P0579 – Cruise Control Multi-Function Input A Circuit Range/Performance (OBD2)

P0579 means "Cruise Control Multi-Function Input A Circuit Range/Performance". The cruise control system signal is electrically present but implausible: it does not match what the control unit expects for the current operating conditions or from other sensors. This is a performance fault, not a broken wire.

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P0579 quick summary

Fault codeP0579
MeaningCruise Control Multi-Function Input A Circuit Range/Performance
SystemPowertrain (Engine & Transmission)
VehiclesGeneric OBD2
SeverityLow
Can I drive?Yes. Only cruise control is affected; the car drives normally.
Repair cost€10 – €400

How cruise control is monitored

Cruise control holds a set speed using signals from the steering column switches, brake and clutch switches and the vehicle speed; these codes cover the switch inputs and, on older systems, the servo and vacuum control.

Modern cruise control is part of the engine control unit: the multi-function switch on the steering column sends on, off, set, resume, accelerate and coast requests, and the electronic throttle holds the speed. Older systems used a separate servo with vacuum and vent valves or a cable actuator.

Codes in this group report faults in the individual switch signals, stuck buttons, implausible combinations (A/B correlation), the servo and its vacuum/vent control, and a vehicle speed that is too high for cruise control.

Cruise control faults do not affect how the engine runs, but the system is disabled. Common causes are worn steering column switches, a faulty clock spring, brake or clutch switch problems and wiring faults.

On VAG vehicles (VW, Audi, Škoda, Seat, Cupra), VCDS and older VAG testers can show this code as the five-digit VAG code 16963 (P0579). Both numbers mean the same fault.

Symptoms of P0579

  • Cruise control does not engage or switches off
  • Buttons do not respond
  • Cruise control indicator flashing
  • Check Engine light on (some vehicles)
  • No effect on normal driving

Most common causes of P0579 (most likely first)

Mechanic's Pro Tip

If cruise control works only intermittently, watch the switch voltage in live data while turning the steering wheel – a failing clock spring shows dropouts at certain angles.

  1. 1.Cruise control system worn, contaminated or out of calibration

    Most likely

    The signal drifts slowly, so it is still within the electrical limits but wrong.

  2. 2.Mechanical problem in the system the cruise control system measures or controls

    For example a leak, a sticking part or a restriction that really changes the measured value.

  3. 3.High resistance in a connector or ground

    Corrosion causes a voltage drop that shifts the reading.

  4. 4.Worn or faulty cruise control switch

  5. 5.Faulty clock spring (steering wheel buttons)

  6. 6.Brake or clutch switch fault

  7. 7.Servo or vacuum/vent valve fault (older systems)

Step-by-step diagnostic guide

  1. 1

    Read codes and switch status

    Read the codes and watch each cruise control switch input in live data while pressing the buttons.

  2. 2

    Compare live data with expected values

    Read the cruise control system values in live data and compare them with related readings (engine speed, load, temperature or pressure) and with the specification. A value that is electrically fine but wrong for the conditions confirms a performance fault – then check the mechanical side before replacing the part.

  3. 3

    Check brake and clutch switches

    Make sure the brake and clutch switch signals are correct – cruise control will not engage if they report 'pressed'.

  4. 4

    Measure the switch

    Check the switch resistances or voltages per button according to the wiring diagram.

    Multimeter: Many multi-function switches use a resistor ladder: each button gives a different voltage on one signal wire.

  5. 5

    Check the clock spring

    If the switch is on the steering wheel, check the clock spring for open circuits (often other steering wheel functions fail too).

  6. 6

    Replace and verify

    Replace the switch or repair wiring and test cruise control on the road.

Frequently asked questions

Can I keep driving with P0579?

Yes. Only cruise control is affected; the car drives normally.

How much does it cost to fix P0579?

Typical repair costs are 10 € – 400 €, depending on the cause and the vehicle. The most common fixes are: cruise control system worn, contaminated or out of calibration; mechanical problem in the system the cruise control system measures or controls; high resistance in a connector or ground. Always confirm the cause with the tests above before buying parts.

Does a cruise control code affect the engine?

No. The engine runs normally; only the cruise function is disabled.

Why does cruise control need the brake switch?

For safety it must disengage when you brake, so a brake switch fault disables it.

What is the difference between P0579 and similar codes?

P0579 belongs to a group of codes for the same component that differ in the type or location of the fault: P0576 – Cruise Control Input Circuit Low; P0577 – Cruise Control Input Circuit High; P0578 – Cruise Control Multi-Function Input A Circuit Stuck; P0580 – Cruise Control Multi-Function Input A Circuit Low; P0581 – Cruise Control Multi-Function Input A Circuit High; P0582 – Cruise Control Vacuum Control Circuit /Open. The tests on this page apply to the whole group; the type of fault tells you where to start.

Related fault codes

This guide is for information only. Working on vehicles can be dangerous — if you are unsure, have the car checked by a qualified mechanic. Values can differ between model years; always check the manufacturer's repair information.