What Does P1502 Mean?
The idle speed control valve closing solenoid circuit shows an abnormal voltage signal. The ECU has detected either a high or low voltage condition when attempting to control the idle air control valve closing function.
Common Causes
35%
Faulty idle air control valve with internal solenoid failure
25%
Short to voltage or ground in IAC valve closing solenoid wiring
20%
Corroded or damaged connector at idle air control valve
12%
ECU internal driver circuit fault for IAC closing solenoid
8%
Carbon buildup causing mechanical binding of IAC valve pintle
Diagnostic Steps
1
Step 1: Inspect IAC valve connector for corrosion, damage, or loose pins
2
Step 2: Measure resistance of IAC closing solenoid coil (typically 10-30 ohms depending on design)
3
Step 3: Check for voltage supply and ground at IAC valve connector with key on
4
Step 4: Test IAC valve control signal from ECU using multimeter or oscilloscope during commanded changes
5
Step 5: Remove IAC valve and clean carbon deposits or replace if solenoid resistance is out of specification
Estimated Repair Cost
$120 - $400
Parts + labor, varies by vehicle and location
The idle speed control valve closing solenoid circuit shows an abnormal voltage signal. The ECU has detected either a high or low voltage condition when attempting to control the idle air control valve closing function.
The most common cause of P1502 (Idle Speed Control Valve Closing Solenoid Control Circuit Signal High or Low) is: Faulty idle air control valve with internal solenoid failure
Typical repair costs for P1502 range from $120 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Engine may idle roughly, stall at stops, or have erratic idle speed. Generally safe to drive but may stall unexpectedly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1502 to identify the root cause.
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Quick Info
Category
Powertrain
System
Idle Air Control System
Difficulty
Type
Manufacturer
Recommended Tools
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