Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means there's a problem with a part in the car that helps control how fast the engine runs when you're not pressing the gas pedal. It's like a switch that isn't working right.
The P1504 code indicates an issue with the idle speed control valve's closing solenoid, which is responsible for regulating the engine's idle speed. An open circuit means there's a break in the electrical connection.
The P1504 code is triggered when the Engine Control Module (ECM) detects an open circuit in the idle speed control valve's closing solenoid. This solenoid is part of the system that manages the engine's idle speed by adjusting the amount of air entering the engine when the throttle is closed.
• Engine stalls at idle
• Erratic idle speed
• Check Engine Light illuminated
• Faulty idle speed control valve
• Open or shorted wiring in the idle control circuit
• Poor electrical connection at the idle speed control valve
Idle Speed Control Valve: A device that regulates the engine's idle speed by controlling the amount of air entering the engine.
Solenoid: An electromechanical device that converts electrical energy into mechanical motion.
• Inspect the idle speed control valve and its wiring for damage.
• Use a multimeter to check for continuity in the idle speed control circuit.
• Test the idle speed control valve for proper operation.
• Replace the idle speed control valve if faulty.
• Repair or replace damaged wiring in the idle control circuit.
• Ensure all electrical connections are secure and free of corrosion.
• Multimeter
• Screwdriver set
• OBD-II scanner
$150 - $300
Moderate
• Ford Focus
• Mazda 626
• Hyundai Elantra
• Regularly inspect and clean the idle speed control valve.
• Ensure electrical connections are tight and corrosion-free.
• Perform routine maintenance checks on the engine's electrical system.
Engine Performance
• If the car stalls frequently, avoid driving until the issue is fixed.
• Have a professional mechanic diagnose and repair the problem.
Check with your vehicle manufacturer for warranty coverage on engine components.
This code has been commonly reported in vehicles with over 100,000 miles or those that have experienced poor maintenance.
Moderate – While the vehicle may still be drivable, the issue can lead to stalling and should be addressed soon.
Driving with a malfunctioning idle control system may lead to unexpected stalling, posing a safety risk.
• Engine at operating temperature
• Vehicle in park or neutral
The idle speed control valve is typically located on the throttle body of the engine.
Q: Can I drive with a P1504 code?
A: It's possible to drive, but it's not recommended as it can lead to stalling and unsafe driving conditions.
Q: How do I reset the Check Engine Light after fixing the issue?
A: You can reset the light using an OBD-II scanner, or it may turn off automatically after a few driving cycles if the issue is resolved.
High-End · Full-system diagnostics
A full-system bidirectional platform aimed at advanced DIY users and professional diagnostic workflows.
Network faults often require full-system access instead of a generic code reader alone.
View on Amazon
Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
View on Amazon
Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.