P0506 — Idle Control System RPM Lower Than Expected
Category: Powertrain Severity: Medium
Updated:
DTC code P0506 means: Idle Control System RPM Lower Than Expected. 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
- Clean the throttle body.
- Check the air filter.
- Perform an idle relearn.
- Check the idle 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
$30–250.
Frequently asked questions
What does DTC code P0506 mean?
Idle Control System RPM Lower Than Expected.
Is code P0506 serious?
Severity Medium. Not urgent, but worth diagnosing to avoid bigger damage.
Can I keep driving with code P0506?
Yes, carefully; the engine may stall.
Related codes
P0505 P0507 P0508 P0509 P0501 P0500 P0521 P0522 P0523 P0530
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