Throttle Actuator Control System - Forced Engine Shutdown
The P2105 code indicates that the Powertrain Control Module (PCM) has detected a fault in the throttle actuator control (TAC) system and has initiated a forced engine shutdown to prevent damage. The TAC system uses an electric motor to control the throttle plate based on accelerator pedal position. When the PCM detects a critical malfunction, such as a short circuit, open circuit, or mechanical failure in the throttle actuator or its circuit, it commands the throttle to close completely, shutting down the engine. This is a safety measure to prevent unintended acceleration or loss of control.
01. Most Common Causes
- Faulty throttle actuator motor
- Open or short circuit in the throttle actuator control circuit
- Failed PCM (rare)
02. Symptoms You Will Notice
- Engine stalls or shuts down unexpectedly
- Check Engine Light illuminated
- Reduced engine power or limp mode
- No response to accelerator pedal
03. Step-by-Step Diagnosis
Step 1: Connect a scan tool and verify the P2105 code. Check for additional related codes.
Step 2: Visually inspect the throttle actuator wiring and connector for damage, corrosion, or loose connections.
Step 3: Test the throttle actuator motor resistance and voltage supply using a multimeter. Compare with manufacturer specifications.
Step 4: If wiring and actuator are okay, perform a throttle body relearn procedure. If code returns, replace the throttle body assembly.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The engine may shut down unexpectedly, causing loss of power steering and brake assist. Have the vehicle towed to a repair shop.
How much does it cost to fix?▼
Diagnosis typically costs $50-$150. Replacing the throttle body assembly can range from $200 to $600 including parts and labor.