What Does P1509 Mean?
An electrical fault has been detected in the idle speed control valve opening solenoid control circuit. This indicates a short circuit, resistance issue, or other electrical abnormality preventing proper opening solenoid operation.
Common Causes
35%
Short to ground or short to power in opening solenoid wiring
30%
Partially shorted or high resistance in opening solenoid coil
20%
Water intrusion or corrosion causing intermittent short in connector
15%
Chafed wiring harness causing intermittent short to chassis or other circuits
Diagnostic Steps
1
Step 1: Disconnect ISC valve connector and inspect for moisture, corrosion, or damaged pins
2
Step 2: Measure opening solenoid coil resistance with ISC valve disconnected (compare to specifications)
3
Step 3: Check for short to ground on opening solenoid control circuit from PCM side with ISC disconnected
4
Step 4: Check for short to voltage on control circuit with key off and ISC disconnected
5
Step 5: Inspect wiring harness for chafing, heat damage, or contact with sharp edges along entire routing
Estimated Repair Cost
$100 - $500
Parts + labor, varies by vehicle and location
An electrical fault has been detected in the idle speed control valve opening solenoid control circuit. This indicates a short circuit, resistance issue, or other electrical abnormality preventing proper opening solenoid operation.
The most common cause of P1509 (Idle Speed Control Valve Opening Solenoid Control Circuit Electrial) is: Short to ground or short to power in opening solenoid wiring
Typical repair costs for P1509 range from $100 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Unstable or erratic idle speed may cause stalling, particularly when additional loads are applied. Low idle or stalling at stops presents safety risk in traffic.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1509 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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