P2100-16 Code: Throttle Actuator Control Motor Circuit Open

Pedal to the floor but the car won't move? P2100 means your Electronic Throttle Body is dead. Use the iCarsoft CR MAX BT to perform a wireless "Butterfly Valve" test.

1. What Does P2100-16 Mean?

The code P2100 stands for "Throttle Actuator Control (TAC) Motor Control Circuit / Open." The extension -16 usually specifies that the circuit voltage is below the required threshold to operate the motor.

Modern cars use Drive-by-Wire technology. There is no cable connecting your foot to the engine. Instead, an electric motor opens the butterfly valve on the throttle body.

P2100 means the "nerve" is cut. The ECU is trying to send power to the throttle motor, but the circuit is broken (Open). The valve stays spring-loaded in the closed position.

3. Why Is the Circuit Open?

It sounds scary, but it's often a simple electrical issue rather than a failed engine component:

Blown ETCS Fuse: The Electronic Throttle Control System has its own high-amp fuse. If the motor worked too hard (due to a dirty, sticky plate), the fuse might pop. Check this first!
Unplugged Connector: Did you recently change the air filter or spark plugs? You might have bumped the throttle body connector loose.
Broken Wires: The wiring harness near the throttle body vibrates constantly. Wires can fray and snap inside the insulation.
Dead Motor: The internal electric motor gears can strip or burn out, creating an open circuit.

4. Diagnosis: The Wireless "Sweep" Test

How do you check if the motor is dead without removing it? You need to watch it move. The iCarsoft CR MAX BT (Bluetooth) allows you to do this from under the hood.

The Wireless Workflow:

Setup: Remove the air intake hose so you can see the metal butterfly plate inside the Throttle Body.
Connect: Plug the VCI dongle in. Take the 7-inch tablet to the engine bay.
Active Test: Select Actuation Test > Throttle Position (or ETCS Test).
Command 0% to 100%: Use the tablet to command the valve to open and close.
- Good: The plate snaps open and closed with a loud "Clack-Clack" sound. (Issue is intermittent wiring).
- Bad: The plate does not move and makes no sound. (Check Fuse first, then replace Throttle Body).

5. Don't Forget the "Relearn"!

If you replace the Throttle Body or even just clean it, the idle will be erratic (too high or surging). The ECU still remembers the "Old" position data.

You MUST perform an Idle Relearn (Throttle Body Adaptation). The CR MAX BT makes this easy:

Go to Service Functions > ETC (Electronic Throttle Control).
Follow the on-screen prompts to teach the ECU the new closed/open positions.
This prevents the dreaded "High Idle" after repair.

Control the Throttle Wirelessly

The iCarsoft CR MAX BT is the perfect tool for Drive-by-Wire diagnostics. Stand over the engine, command the throttle plate, and verify the fix visually without needing a helper to press the pedal.

Bi-Directional: Perform Throttle Sweep tests.
7-inch Touchscreen: Clear interface for Idle Relearn.
Wireless Bluetooth: Diagnose from the engine bay.

Shop CR MAX BT

6. Frequently Asked Questions

Q: Can I manually push the throttle plate open to check it?
A: Be careful. On some cars, manually forcing the electric motor gears can strip them. It is always safer to use an electronic scan tool like the CR MAX BT to command it open.

Q: Will cleaning the throttle body fix P2100?
A: Usually no. Cleaning fixes sticky pedals or rough idle. P2100 is an electrical circuit break. Cleaning won't reconnect a cut wire.

Q: Is the fuse labeled "Throttle"?
A: Usually it is labeled ETCS, TAC, or DBW in the fuse box diagram.