P0579 — Cruise Control Multi-Function Input A Circuit Range/Performance
Drive with caution — fix soon.
What P0579 means
This code means the cruise control multi-function input A signal is outside its expected range or doesn't perform as designed. It usually points to a faulty cruise control switch, resistance problems in the wiring, or a poor connection. It's a common, repairable fault that's typically resolved with a switch or wiring fix rather than serious engine work.
Common symptoms
- Check engine light is on
- Cruise control does not set or hold speed
- Cruise control engages at the wrong setting
- Erratic or unresponsive cruise control buttons
- Cruise warning indicator may appear
Common causes
- Faulty cruise control switch
- Out-of-spec resistance in the input wiring
- Corroded or damaged connector
- Loose or intermittent electrical connection
- Failing cruise control or engine control module
Typical repair cost
$100 – $350
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0579 code?
Usually yes. The engine runs fine, but cruise control may not work correctly, so be ready to manage your speed manually until the issue is fixed.
How much does it cost to fix a P0579 code?
Most repairs fall between $100 and $350. Diagnosing and repairing wiring or a connector is cheaper than replacing the cruise control switch or module.
Is a P0579 code serious?
It's a moderate issue. Your engine isn't at risk, but the out-of-range signal usually means a switch or wiring fault that should be checked before cruise control fails entirely.
What does range/performance mean for this code?
It means the cruise control input signal is present but reads outside the normal range the computer expects, often due to a worn switch or wiring resistance problem.