P0509

Idle Air Control System Circuit High

Severity

⚠️ Medium

Can you drive?

Limited driving only, diagnose soon

Approx. repair cost

$33–111 (est.)

Symptoms

Unstable idle
Floating engine speed
Engine stalls at idle
Increased fuel consumption

Causes

Idle air speed sensor (IAC) malfunction
Open or short circuit in wiring harness
Poor contact in connectors
ECU malfunction
Throttle valve contamination

How to Fix

Check the status of the idle air speed sensor (IAC)
Inspect the wiring harness for damage
Check contacts in connectors
Clean throttle body
If necessary, replace the idle speed sensor

Related codes

P0507 P0508 P0510