Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
Your car's computer is having trouble controlling the engine's idle speed, which is how fast the engine runs when you're not pressing the gas pedal.
The P0505 code indicates that the engine's idle control system is not functioning properly, causing the idle speed to be too high or too low.
The Idle Air Control (IAC) system is responsible for maintaining the engine's idle speed by regulating the amount of air entering the engine when the throttle is closed. A P0505 code is triggered when the Engine Control Module (ECM) detects a fault in this system, such as incorrect idle speed or a malfunctioning IAC valve.
• Erratic or high idle speed
• Engine stalling
• Check Engine Light illuminated
• Faulty Idle Air Control (IAC) valve
• Vacuum leaks
• Dirty throttle body
ECM: Engine Control Module
IAC: Idle Air Control
• Inspect the IAC valve for damage or blockage.
• Check for vacuum leaks in the intake system.
• Clean the throttle body and IAC passages.
• Replace the faulty IAC valve.
• Repair any vacuum leaks.
• Clean the throttle body.
• OBD-II scanner
• Screwdriver set
• Throttle body cleaner
$100 - $300
Moderate
• Honda Civic
• Toyota Camry
• Ford F-150
• Regularly clean the throttle body.
• Check for and repair vacuum leaks promptly.
• Perform routine maintenance on the IAC valve.
Engine Performance
• Avoid driving with a high idle speed to prevent engine damage.
• Seek professional diagnostic help if unsure about repairs.
Check with your vehicle manufacturer for warranty coverage on emissions-related components.
The P0505 code has been common in vehicles with electronic throttle control systems since the introduction of OBD-II standards.
Moderate – While not immediately dangerous, prolonged issues can lead to engine performance problems.
Driving with a malfunctioning idle control system can lead to safety issues and increased emissions.
• Engine at operating temperature
• Vehicle in park with no load
The Idle Air Control (IAC) valve is typically located on or near the throttle body of the engine.
Q: Can I drive with a P0505 code?
A: It's not recommended as it can lead to engine performance issues and increased emissions.
Q: How do I reset the P0505 code?
A: After repairs, use an OBD-II scanner to clear the code from the vehicle's computer.
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