Idle Control System Malfunction
The idle control system did not operate as expected during the computer's check. Some vehicles use a separate idle-air valve, while others manage idle through the electronic throttle. P0505 does not automatically mean there is an idle valve to replace. Air leaks, actuator faults and control problems require vehicle-specific diagnosis, especially if behavior changes when stopping or selecting a gear.
Can I keep driving?
High idle that pulls the vehicle, unpredictable throttle response, stalling or abnormal braking calls for a safe stop and towing. With no symptoms and a steady light, ask a shop before further driving; do not adjust idle yourself.
What does this code mean for your car?
The same code can need different checks depending on the model and engine. Enter your vehicle details to find relevant sources and checks.
Symptoms
- Surging or unusually high idle
- Stalling at a stop
- Hard starting or rough operation
Possible causes
- 1Idle actuator or throttle fault depending on system
- 2Intake air leak
- 3Damaged idle-control wiring or connector
- 4Deposits or an adaptation issue requiring the manufacturer procedure
These possibilities are not ranked by frequency and do not diagnose your vehicle.
Checks you can safely do yourself
Safe checks only: engine off and cold, car on level ground.
- Save the code and freeze-frame data if your scanner offers them, without clearing anything.
- With the engine off and cool, look for visibly detached accessible intake hoses; do not turn a stop screw or move the throttle plate.
When you need a shop
Request identification of the idle-control design, unmetered-air and wiring checks, and comparison of target idle with actual operation. Cleaning or relearning should follow the manufacturer procedure only when findings justify it.
How much does it cost?
A US repair estimate needs a diagnosis and a local shop quote.
No verified US repair quote is available for this fault. The price depends on diagnosis, vehicle, parts and local labor; request 2-3 itemized quotes.
Get 2-3 quotes
Investigate this code for my carFAQ
Can I keep driving with P0505?
High idle that pulls the vehicle, unpredictable throttle response, stalling or abnormal braking calls for a safe stop and towing. With no symptoms and a steady light, ask a shop before further driving; do not adjust idle yourself.
What can cause P0505?
Possible causes include idle actuator or throttle fault depending on system; intake air leak; damaged idle-control wiring or connector; deposits or an adaptation issue requiring the manufacturer procedure. These are diagnostic possibilities, not a confirmed diagnosis or a parts shopping list.
Does clearing the code fix the problem?
No. Clearing a code does not repair the problem or prove that no fault exists. It may erase useful evidence and reset readiness monitors. Save codes and freeze-frame data first; confirming a repair requires the vehicle-specific checks.
What if this code appears during a used-car inspection?
Arrange an independent professional pre-purchase inspection before committing. Request a complete scan, readiness status and diagnosis of the relevant system. Get written findings and a repair estimate; an unlit warning lamp does not replace inspection.
How much does a P0505 repair cost?
No verified US repair quote is available for this fault. The price depends on diagnosis, vehicle, parts and local labor; request 2-3 itemized quotes.