P0579 OBD-II Trouble Code: Cruise Control Multi-Function Input A Circuit Range/Performance

Our certified mechanics come to you · Get a fair and transparent estimate upfront


Cost of diagnosing the P0579 code

P0579 is a diagnostic trouble code (DTC) for "Cruise Control Multi-Function Input A Circuit Range/Performance". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $154.99 . Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $50.0 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate* Credit towards follow-up repair Earliest Availability
Ford $154.99 $50.0
Toyota $154.99 $50.0
BMW $164.99 $50.0

*Estimates may vary by market

SCHEDULE P0579 DIAGNOSTIC Get a fair and transparent estimate upfront

P0579 OBD-II Trouble Code: Cruise Control Multi-Function Input A Circuit Range/Performance

P0579 code definition

The P0579 code signifies that the car’s computer has found a malfunction in the cruise control multi-function input A circuit.

What the P0579 code means

If your car’s computer notes a malfunction in the cruise control multi-function input A circuit, it will set the P0579 code and may turn on the Check Engine light. The multi-function input circuit is really just the control switch for the cruise control system. It allows you to set a speed, resume, accelerate, decelerate and more. However, if it malfunctions, the cruise control system will not be able to be controlled safely, so the computer will turn it off and set a warning code.

What causes the P0579 code?

A couple of different causes may set the P0579 code, including the following:

  • A faulty cruise control switch
  • Damage from liquids spilled on the cruise control switch
  • Damaged wiring
  • An open or short in the cruise control circuit
  • A blown fuse (often a symptom, but sometimes a cause)

What are the symptoms of the P0579 code?

There are very few symptoms associated with the P0579 code. The car’s Check Engine light may or may not come on. The cruise control system will be inoperable until the problem is fixed.

How does a mechanic diagnose the P0579 code?

Diagnosing the P0579 code requires the mechanic to first connect an OBD II scanner to the car’s computer. The codes will be read, noted and then cleared, and the car will be test driven to see if the codes reset. The mechanic should also test the cruise control system for operation during the test drive.

If the codes return and/or the cruise control system remains inoperable, the mechanic should test the cruise multi-function switch for operability. This is the single most common cause of the code. Doing so will require that the vehicle be put on a lift, with an assistant operating the gas pedal and the engine running. The mechanic will use a scanner to test the switch for operation. If it fails the test, the switch should be replaced.

If the switch operates normally, the mechanic should check the wiring and connectors for opens, shorts and other damage, as well as for loose or corroded connections. Any damage should be repaired, or damaged sections replaced.

The mechanic should also check cruise control fuses prior to and after replacing any parts, as blown fuses are often associated with this particular code.

Common mistakes when diagnosing the P0579 code

One common mistake here is not checking for blown fuses prior to replacing components. Often, a blown fuse can mimic symptoms of switch failure, as can issues like loose connections or broken wires.

How serious is the P0579 code?

The P0579 code is not particularly serious and will not prevent your car from being driven. However, until the problem is fixed, your cruise control system will be inoperable, which can be inconvenient and lead to discomfort and fatigue during long drives. Have the problem diagnosed soon.

What repairs can fix the P0579 code?

In most cases, fixing the P0579 code requires replacing a faulty cruise control switch. However, this is just one of several possible causes. Other potential fixes include:

  • Replacing damaged wiring
  • Cleaning or tightening connections
  • Replacing blown fuses

Additional comments for consideration regarding the P0579 code

While the P0579 code isn’t serious enough to affect drivability, the inconvenience can be significant, particularly if you spend a lot of time driving on highways or interstates.

Need help with a P0579 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

Check Engine Light
trouble codes

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0579 code.

Get a $50 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating


Rating Summary
 at YourMechanic


9 years of experience
133 reviews
9 years of experience
Ford Escort L4-2.0L - Check Engine Light is on - Nashville, Tennessee
Brandon showed up ahead of schedule, was very personable and diagnosed my problems. He also scheduled my next appointments which will be with him.
 at YourMechanic


23 years of experience
33 reviews
23 years of experience
Lexus IS250 V6-2.5L - Check Engine Light is on - Mableton, Georgia
Arrived early which was great. William was courteous, and attentive to the issue. Even though it took several attempts I'm so happy he was determined to fix it and he did!
 at YourMechanic


40 years of experience
1080 reviews
40 years of experience
Plymouth Grand Voyager - Check Engine Light is on - Lawrenceville, Georgia
Mr. Dan Barber was quite patient, courteous and quite knowledgeable. From my observation, Mr. Barber appears to be quite professional.
 at YourMechanic


9 years of experience
120 reviews
9 years of experience
Ford Fiesta L4-1.6L - Check Engine Light is on - Smyrna, Georgia
Chris communicated with us each step of the way up until his arrival. He listened well, was knowledgeable, and was prepared. He took the time to diagnose the problem, explained the what, why and how and provided a solution. I would definitely recommend him and will use him again.

More related articles

P3487 OBD-11 Trouble Code: Cylinder Exhaust Valve Control low
What What the P3487 code means This code indicates that there is a problem with the exhaust valve on cylinder number 11. Your vehicle’s powertrain control module (PCM) can recognize that the measured values of the mass airflow sensor, the...
P0515 OBD-II Trouble Code: Battery Temperature Sensor Circuit
P0515 trouble code means there is an issue with the battery temperature sensor circuit often caused by battery corrosion or engine overheating.
P0776 OBD-II Trouble Code: Pressure Control Solenoid B Performance
P0776 code means there is an abnormality within either the electronic pressure control circuit or solenoid often due too dirty fluids or faulty parts.

Related questions

Can shaft position sensor all of the outcomes of the problem
Possibilities: 1 - Simply replacing the camshaft sensor (https://www.yourmechanic.com/services/camshaft-position-sensor-replacement) will solve your problem. 2 - If it does not, with the age of the vehicle, there can be a break in the wiring harness to the cam sensor. 3 -...
Oil light came on and the oil is full.
Hi there. Either the oil pump in the engine has failed and is pushing oil at a lower pressure than the sending unit could register or the sending unit failed. If you need further assistance with your warning lights (https://www.yourmechanic.com/services/warning-light-is-on-inspection),...
2013 Subaru Impreza. Speedometer not working. Abs light on check engine light on and brake light on what could be going on?
Hello, thank you for writing in. The multiple lights coming on is a sign that one of the major components in the vehicle is failing. Considering the lights all seem to be related to the ABS or wheel speed sensors,...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com