P0509 - Idle Control System Circuit High
The idle control circuit signal is higher than expected.
Treat the code as the starting point: compare symptoms, likely causes, and repair paths before pricing parts or moving into an estimate.
Code Overview
The idle control circuit signal is higher than expected.
Common Causes
- Failed sensor or idle control component
- Damaged wiring or connector
- Throttle body or switch issue
Diagnostic Steps
- Inspect the related connector and harness
- Compare live data to vehicle behavior
- Check for mechanical sticking or adjustment problems
Likely Repairs & Cost Guides
Use symptoms, scan data, and quick checks to confirm the likely repair path before pricing parts. The estimator helps compare repair paths before replacing anything unnecessarily.
Continue EstimateRelated OBD Codes
Browse nearby code-family pages when the same fault pattern overlaps across systems, such as misfire, lean fuel trim, EVAP sealing, cooling, or charging faults.
Next Steps
Move from code lookup to diagnosis, then estimate the likely repair only after symptoms, causes, and checks point to the same path.