Engine died and won't restart? P2105 is the ECU's "Nuclear Option." It detected a massive safety risk and cut the power. Use the iCarsoft CR MAX BT to find out why.
1. What Does P2105 Mean?
The code P2105 stands for "Throttle Actuator Control System - Forced Engine Shutdown."
This is one of the most severe codes your car can trigger. It means the Engine Control Unit (ECU) decided that the throttle system was malfunctioning so badly that it was unsafe to keep the engine running.
🛑 The Engine Will Not Run
Unlike P2104 (Forced Idle), which lets you limp home slowly, P2105 kills the engine completely. It cuts off fuel and spark to prevent runaway acceleration.
2. The "Kill Switch" Logic
Why would the car do this? Imagine if your throttle butterfly valve got stuck wide open while you were sitting at a red light. You would launch into traffic.
To prevent this, the ECU monitors the throttle sensors. If it sees conflicting data or a total loss of control, it executes P2105 as a fail-safe.
The Hierarchy of Throttle Codes:
| Code | Action | Severity |
|---|---|---|
| P2101 | Warning Light | Check Engine Light On. |
| P2104 | Forced Idle | Limp Mode (Max 5-10 MPH). |
| P2105 | Engine Shutdown | Stalled. Won't Start. Tow Truck needed. |
3. What Triggered the Shutdown?
P2105 is the Result, not the Cause. You must find the other codes stored alongside it to fix the car.
- Massive Short Circuit: If P2103 (Circuit High) occurs, sending 12V into the ECU, the computer shuts down to save itself from burning out.
- Throttle Stuck Open: If the butterfly valve jams (ice, carbon, or broken gear) and refuses to close, the ECU kills the engine.
- ECU Internal Failure: If the processor detecting the throttle position fails, it assumes the worst and shuts down.
4. Diagnosis: Wireless "Freeze Frame" Analysis
Since the engine likely won't start (or dies immediately), you can't test drive it. You need to look at the history of what happened the moment it died. This is where the iCarsoft CR MAX BT shines.
Step 1: Wireless Scan (No-Start Condition)
- Turn the ignition ON (Engine Off).
- Use the CR MAX BT to perform an "All Systems Scan" wirelessly.
- Read Codes: Look for the other codes. Is there a P2101? A P2135? Fix those first.
Step 2: Read Freeze Frame Data
- In the CR MAX BT menu, select Freeze Frame.
- This shows you the exact data (RPM, Voltages, Temp) at the split second P2105 triggered.
- Clue Hunting: Did the system voltage spike to 16V? (Alternator issue). Did the Throttle Position read 100% at idle? (Stuck throttle).
Step 3: Clear and Crank
- Clear the codes. Try to start the engine while watching Live Data on the 7-inch tablet.
- If the throttle position sensors (TP1 and TP2) don't move or show erratic numbers while cranking, you have found the faulty sensor or wire.
Decode the Shutdown
When your car won't start, you need answers fast. The iCarsoft CR MAX BT lets you pull Freeze Frame data and read hidden manufacturer codes wirelessly, helping you decide if you can fix it there or need a tow.
- Freeze Frame: See exactly why the engine died.
- Wireless Bluetooth: Diagnose without sitting in a hot/cold car.
- All-Systems Scan: Find the root cause behind P2105.
Shop CR MAX BT
6. Frequently Asked Questions
Q: If I clear P2105, will the car start?
A: Maybe, but be careful. Clearing the code resets the "Shutdown" command. The car might start, but if the underlying problem (like a stuck throttle) is still there, it will likely trigger P2105 and die again immediately.
Q: Is the Throttle Body ruined?
A: Not always. If the shutdown was caused by an electrical short in the harness (wiring), the throttle body itself might be fine. Always check wiring before buying parts.
Q: Can a bad battery cause P2105?
A: Yes! If system voltage drops too low (dead battery) or spikes too high (bad alternator), the throttle actuator can glitch, scaring the ECU into a forced shutdown.
