P0505 Idle air control system
What P0505 means
The engine control unit is trying to control idle speed but the actual speed does not follow the target. On older engines this is the idle air control valve; on newer ones the electronic throttle does the job.
P0505 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
- 50–350 €
- Workshop time
- 0.3–2.5 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
- Idle speed too high, too low or hunting
- Stalling when stopping or when the A/C switches on
- Check engine light on
Common causes
- Carbon build-up in the throttle body or idle air control valve
- Failed idle air control valve
- Vacuum leak from a hose, intake gasket or PCV system
- Faulty wiring to the idle control valve
- Idle relearn not done after battery disconnection or cleaning
Can I keep driving with P0505?
You can keep driving, but have it checked within one to two weeks. If the engine stalls at junctions, take extra care in traffic.
What to check first
- Check for vacuum leaks around hoses and the intake
- Clean the throttle body and idle air passage
- Perform the idle relearn procedure for your car
- Test or replace the idle air control valve if fitted
Related codes
- P0504 Brake switch A/B correlation
- P0506 Idle control system RPM lower than expected
- P0503 Vehicle speed sensor A intermittent/erratic/high
- P0507 Idle control system RPM higher than expected
- 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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