Is your ECU confusing itself? P2107 means the internal "brain" controlling the throttle has failed a self-test. Before you spend $1,000 on a new computer, check your battery voltage with the CR MAX BT.
1. What Does P2107 Mean?
The code P2107 stands for "Throttle Actuator Control (TAC) Module Processor."
⚠️ The Engine Brain is Confused
Unlike codes pointing to a broken wire (P2100) or a stuck plate (P2111), P2107 is an internal logic error. The ECU runs a self-diagnostic test on its own math chips. This code means the processor responsible for the throttle said: "My calculations don't match reality. I am shutting down for safety."
Because the ECU doesn't trust its own brain, it will immediately trigger Limp Mode or shut the engine down completely.
2. Internal Error vs. External Cause
When mechanics see "Module Processor Failure," they often assume the computer is fried and quote you for a new ECU (PCM). Stop!
Computers are sensitive. If you feed them "bad power," they make math errors.
- The "Hangover" Analogy: If a person is dehydrated and tired, they can't do complex math. The brain isn't damaged; it just lacks resources.
- The ECU Reality: If your battery voltage drops too low during cranking, or if a ground wire is loose, the ECU chip "browns out" and fails its self-test, triggering P2107.
3. Why Did the Processor Fail?
Before replacing the expensive computer, check these common culprits:
- Low Voltage (Most Common): A weak battery or a dying alternator causes voltage fluctuations. The TAC module is extremely sensitive to this.
- Bad Ground: If the ECU's ground wire is corroded, the electrical "noise" will confuse the processor.
- Shorted Throttle Body: Sometimes, an external short in the throttle motor (P2103) sends a power spike backwards into the ECU, physically damaging the driver chip.
- ECU Failure: Yes, sometimes the computer is actually dead. But this is the last thing you should assume.
4. Diagnosis: The Wireless Voltage Monitor
You need to prove that the ECU is getting clean, stable power. The iCarsoft CR MAX BT (Bluetooth) lets you monitor this while cranking the engine from outside.
Step 1: The Cranking Volts Test
- Setup: Connect the VCI dongle. Take the 7-inch tablet.
- Select Data: Go to Live Data > Control Module Voltage (or System Voltage).
- Graph Mode: Switch to graph.
-
Action: Crank the engine. Watch the lowest point on the graph.
- Good: Voltage stays above 10V during cranking.
- Bad: Voltage drops below 9.5V. This "brownout" is likely causing the P2107 logic error. Replace the battery.
Step 2: The "Ghost" Check
- Clear the P2107 code with the CR MAX BT.
- Turn the key OFF for 30 seconds.
- Turn Key ON (Do not start). Does P2107 return immediately?
- Yes: The ECU is likely hard-failed (Internal Damage).
- No: It was likely a "glitch" caused by the previous low voltage event.
Diagnose Voltage & Computers
The iCarsoft CR MAX BT is more than a code reader; it's a system monitor. Use the wireless graphing to check battery health and ECU stability before you waste money on unnecessary computer replacements.
- Wireless Graphing: Catch voltage drops during cranking.
- All-Systems Scan: Check if other modules have low voltage codes.
- Battery Reset: Register your new battery after replacement.
6. Frequently Asked Questions
Q: If I replace the ECU, do I need to program it?
A: Yes. You cannot just swap in a used ECU from a junkyard. It must be programmed with your VIN and security (immobilizer) data, or the car will not start.
Q: Can a bad throttle body cause P2107?
A: Indirectly, yes. If the throttle motor shorts out, it can damage the ECU's internal driver. If you replace the ECU, always replace the throttle body too, or the old throttle body might fry your new ECU instantly.
Q: Can I drive with P2107?
A: No. The car will be in strict Limp Mode (no acceleration) or will shut down completely. It is a major safety system failure.
