P0506 Idle control system RPM lower than expected
What P0506 means
The engine control unit wants a certain idle speed but the engine is running slower than that and the ECU cannot raise it enough. Not enough air is getting past the throttle at idle, or something is dragging the engine down.
P0506 is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- Medium
- Typical repair cost
- 20–350 €
- Workshop time
- 0.3–2 h
- Repair difficulty
- Easy
- DIY possible
- Yes
- Check engine light
- Yes
- Affects emissions test
- Yes
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Low or rough idle
- Engine stalling when stopping
- Vibration at idle
- Idle dips when A/C or lights switch on
Common causes
- Carbon deposits in the throttle body
- Dirty or failing idle air control valve
- Restricted air filter or intake
- Extra load from a failing alternator or A/C compressor
- Idle relearn not completed
Can I keep driving with P0506?
You can keep driving, but have it checked within one to two weeks. Cleaning the throttle body is the usual first step.
What to check first
- Check the air filter and intake for blockage
- Clean the throttle body and idle air passages
- Perform an idle relearn
- Test the idle air control valve and check for unusual accessory load
Related codes
- P0505 Idle air control system
- P0507 Idle control system RPM higher than expected
- P0504 Brake switch A/B correlation
- P0503 Vehicle speed sensor A intermittent/erratic/high
- P0502 Vehicle speed sensor A circuit low
- P0501 Vehicle speed sensor A range/performance
- P0500 Vehicle speed sensor A circuit
- P0510 Closed throttle position switch
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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