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P0509 — IAC System Circuit High

Idle air control circuit voltage too high.

Severity: MediumRepair: $50-$400Difficulty: Easy

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Common symptoms of P0509

High idle
Check engine light

Common causes of P0509

Failed IAC valve
Wiring short to voltage
Open circuit

Repair cost & difficulty

Typical cost to fix P0509: $50-$400 · Difficulty: Easy

Pro tip: Check IAC valve connector.

Vehicles commonly affected

All makes

Related trouble codes

P0505 P0507 P0508

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ScanFixAI is a diagnostic aid, not a substitute for professional repair. Cost estimates are typical ranges and vary by vehicle and region.