P0578 OBD-II Trouble Code: Cruise Control Multi-Function Input "A" Circuit Stuck

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


Cost of diagnosing the P0578 code

P0578 is a diagnostic trouble code (DTC) for "Cruise Control Multi-Function Input "A" Circuit Stuck". 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. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 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
SCHEDULE P0578 DIAGNOSTIC Get a fair and transparent estimate upfront

P0578 code definition

The P0578 code is detected in instances where the PCM registered a malfunction with the cruise control multi-function input circuit.

What the P0578 code means

In order to control vehicle speed when the cruise control is activated, the cruise control system works with the PCM to monitor the operation. If the PCM detects that the vehicle speed is not being automatically controlled by the cruise control, it will initiate a self-test of the system. If, during this test, an abnormal voltage reading is detected in the cruise control multi-function input circuit, the PCM will store the P0578 code.

What causes the P0578 code?

In most cases, this code is caused by a failed cruise control switch, especially if the cruise control button has had liquid spilled on it, or if dust or debris has been allowed to build up on the buttons. Other causes may include:

  • Shorted, damaged, or open wiring, connectors, or wiring
  • Blown fuses, which may indicate a more serious issue

What are the symptoms of the P0578 code?

In most cases, the cruise control will not work, and the Check Engine light will activate within two to three drive cycles after the PCM has detected the issue.

How does a mechanic diagnose the P0578 code?

After an OBD-II scanner detects the P0578 code, a technician will perform visual inspection of all the wiring, connectors, and other electrical components of the cruise control system. After repairing or replacing any components, they should then clear the code and perform a test drive, checking that the cruise control works as it should, and that the Check Engine light does not reappear. This process should be repeated after each attempted repair, to ensure that no unnecessary repairs are performed. If this process does not fix the issue, it is likely that the cruise control switch is faulty, and needs to be replaced.

Common mistakes when diagnosing the P0578 code

When diagnosing the underlying cause of the P0578 code, the most common mistake is forgetting to disconnect the PCM and the cruise control module when testing circuit resistance. It is also important to check for blown fuses before replacing any parts – a blown fuse will cause a new replacement part to fail just as the old one did.

How serious is the P0578 code?

If the P0578 code is not considered an emergency that must be fixed right away. The vehicle will still be operable, and only the cruise control function is likely to be interrupted. However, if a blown fuse is part of the problem, that may cause other electrical issues that can lead to unsafe driving conditions – such as losing the ability to activate the turn signal. In this case, the P0578 code would need to be addressed right away.

What repairs can fix the P0578 code?

In order to repair the P0578 code, a mechanic may replace the cruise control switch, repair or replace any damaged electrical components, and/or replace any burnt fuses.

Additional comments for consideration regarding the P0578 code

While the P0578 code is stored in the PCM, the vehicle may not be able to pass an OBD-II emissions test. In states where emissions tests are required, this could mean that the vehicle will not be legally registered for use on public roadways.

Need help with a P0578 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.

trouble codes
Check Engine Light

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0578 code.

Get a $20 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating

YourMechanic Check Engine Light is on Inspection Service

Average Rating


Number of Reviews


Rating Summary


11 years of experience
104 reviews
11 years of experience
Nissan Quest - Check Engine Light is on - Alexandria, Virginia
Punctual. Knowledgeable. Professional. Empathic, went the extra mile to explain in lay words the mechanical jargon. Excellent manners and customer service oriented. Client’s best interest and safety was always his top priority. From now on your company has in me a client for life. Thanks Robert!!!! 


21 years of experience
1861 reviews
21 years of experience
Mercedes-Benz E320 - Check Engine Light is on - Ladera Ranch, California
Chris was friendly, professional and knowledgeable. He got to the point of my concerns, explained what he was finding on his system and gave me his recommendations. I fully appreciate him taking the time to explain everything and a bit of history on my vehicle. Thanks again Chris.


15 years of experience
574 reviews
15 years of experience
Hyundai Accent - Check Engine Light is on - Marietta, Georgia
I had a great experience with Michael. He's extremely professional, friendly, and understands his craft. Highly recommended.


15 years of experience
274 reviews
15 years of experience
Dodge Durango - Check Engine Light is on - San Diego, California
Showed up early, was a friendly dude, kept me informed via text, did clean work and finished early. Would hire again.

More related articles

Related questions

Bad gas in tank of 2008 Toyota 4Runner

The first step in dealing with bad gas is removing it from the fuel system as quickly as possible. This will help prevent further damage to any of the fuel system components. To do this, it will require that the...

2010 Ford Fusion SE with I4 Engine - Throttle Position (TP) and Accelerator Pedal Position (APP) sensors

Since the code reads Throttle Body, the sensor on the throttle body under the hood may be the best place to start. The throttle position sensor measures the angle of the throttle plate and tries to match the effort shown...

Oil leaking occasionally

When oil is actively hitting the ground in the amounts you have described there is a problem. The oiling system should be self contained and is not supposed to leak. It is possible that the leak wasn't apparent or the...

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