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


8 years of experience
22 reviews
8 years of experience
Chrysler PT Cruiser - Check Engine Light is on - Los Angeles, California
He was very courteous and knowledgeable. You can tell he knows his trade. Satisfied with his service.


8 years of experience
91 reviews
8 years of experience
Nissan Versa Note - Check Engine Light is on - Upper Darby, Pennsylvania
Yoel is very competent and provides great customer service. He took the time to explain and show me exactly what was going with my car. I will definitely use him again and recommend him to others.


31 years of experience
148 reviews
31 years of experience
Ford Explorer - Check Engine Light is on - Phoenix, Arizona
Jason was on time, friendly, explained everything he was doing and let me know the other services available, so when Jason comes back to install the new part I am having the oil changed too.


25 years of experience
1 reviews
25 years of experience
BMW X3 - Check Engine Light is on - Moreno Valley, California
The mechanic arrived on time, completed the work, which was replacement of an oxygen sensor, in a timely and professional manner.

More related articles

Related questions

Codes p0101, p0131, p0137, p0151 & p0327 I guess I'm asking would replacing the ECM solve the problem? 2002 Chevrolet Blazer

Hello - the codes you list (besides the P0101 for the MAF) reference problems with the oxygen sensors and a knock sensor (P0327) for your engine. These are normal higher mileage maintenance items, and do NOT require replacing the ECU....

Car starts and then turns off

I would recommend starting with having your vehicle checked for trouble codes with an OBD2 scanner. Once the codes have been pulled by a knowledgable technician, a strategic diagnosis plan can be made. The Check Engine Light code will aid...

The P0010 error keep coming up and my car keeps jumping, and turning itself off and on while I drive sometimes.

Hello, thanks for writing in. If you took your vehicle in for repairs, and it was returned with a check engine light then I would immediately return to the shop and have them take care of the issue. If 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.

1-800-701-6230 · hi@yourmechanic.com