What Does P1508 Mean?
The PCM has detected an open circuit in the idle speed control valve opening solenoid control circuit. The opening solenoid cannot be energized to increase idle speed, preventing proper idle control.
Common Causes
35%
Broken wire or open circuit in opening solenoid control wiring
30%
Failed idle speed control valve opening solenoid coil
25%
Disconnected or severely corroded connector at ISC valve
10%
PCM driver circuit failure for opening solenoid
Diagnostic Steps
1
Step 1: Inspect ISC valve connector for proper seating, corrosion, or damaged/pushed-out pins
2
Step 2: Measure resistance of opening solenoid coil at ISC valve connector (typically 10-30 ohms)
3
Step 3: Verify battery voltage at ISC valve power supply terminal with key on
4
Step 4: Check continuity of opening solenoid control circuit from ISC valve to PCM connector
5
Step 5: Back-probe PCM opening solenoid control wire and verify switching ground signal during commanded opening
Estimated Repair Cost
$100 - $450
Parts + labor, varies by vehicle and location
The PCM has detected an open circuit in the idle speed control valve opening solenoid control circuit. The opening solenoid cannot be energized to increase idle speed, preventing proper idle control.
The most common cause of P1508 (Idle Speed Control Valve Opening Solenoid Control Open Circuit) is: Broken wire or open circuit in opening solenoid control wiring
Typical repair costs for P1508 range from $100 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Engine may idle too low or stall, especially under load conditions like air conditioning operation. Stalling at stops creates traffic safety concerns.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1508 to identify the root cause.
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Quick Info
Category
Powertrain
System
Idle Speed Control
Difficulty
Type
Manufacturer
Recommended Tools
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