P0508 — Idle Air Control System Circuit Low
Category: Powertrain Severity: Medium
Updated:
DTC code P0508 means: Idle Air Control System Circuit Low. It falls under the "Powertrain" category, with an estimated severity of Medium. Common causes include dirty or carbon-fouled throttle body, faulty idle air control (IAC) valve and vacuum leak; it's worth confirming the diagnosis before replacing parts.
Possible causes
- Dirty or carbon-fouled throttle body
- Faulty idle air control (IAC) valve
- Vacuum leak
- Wiring/connector issue on the IAC circuit
Symptoms
- Rough, unstable or low idle
- Engine stalling at idle or stops
- Check engine light on
- Idle surging (RPM rising and falling on its own)
How to diagnose it step by step
- Check the idle valve connector.
- Test the valve.
- Replace the valve.
How to fix it
Clean the throttle body and IAC valve first — carbon buildup is the most common cause and this alone often fixes it. Check for vacuum leaks around the intake before replacing the IAC valve or its wiring.
Estimated repair cost
$80–250.
Frequently asked questions
What does DTC code P0508 mean?
Idle Air Control System Circuit Low.
Is code P0508 serious?
Severity Medium. Not urgent, but worth diagnosing to avoid bigger damage.
Can I keep driving with code P0508?
Yes, carefully.
Related codes
P0507 P0509 P0506 P0505 P0501 P0500 P0521 P0522 P0523 P0530
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