What Does P1581 Mean?
The idle speed control system has not completed its basic throttle position calibration or adaptation procedure. This prevents the PCM from properly controlling idle speed and throttle operation.
Common Causes
40%
Throttle body not properly cleaned or calibrated after service
30%
Electronic throttle body mechanical fault or carbon buildup
15%
Battery disconnection or voltage drop during adaptation procedure
15%
Failed throttle position sensor within throttle body
Diagnostic Steps
1
Step 1: Perform throttle body cleaning and remove carbon deposits from throttle plate and bore
2
Step 2: Execute manufacturer-specific throttle body basic setting/adaptation procedure using scan tool
3
Step 3: Verify battery voltage remains stable above 12.5V during entire adaptation process
4
Step 4: Check for vacuum leaks and ensure all intake system connections are sealed
5
Step 5: Monitor throttle position sensor values at closed throttle (should be 0-5% typically)
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
The idle speed control system has not completed its basic throttle position calibration or adaptation procedure. This prevents the PCM from properly controlling idle speed and throttle operation.
The most common cause of P1581 (Idle Speed Contr.Throttle Pos. Basic Setting Not Carried Out) is: Throttle body not properly cleaned or calibrated after service
Typical repair costs for P1581 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
May cause rough idle, stalling at stops, or erratic throttle response. Vehicle generally safe to drive but may stall unexpectedly in traffic.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1581 to identify the root cause.
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Quick Info
Category
Powertrain
System
Idle Air Control / Electronic Throttle
Difficulty
Type
Manufacturer
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