P2104 Code: Throttle Actuator Control System - Forced Idle

What the P2104 code means

With an electronic throttle (drive by wire), there is no cable between the pedal and the throttle. The computer reads the pedal, works out how far the throttle should open and moves it with a small electric motor. Two position sensors on the throttle and two more on the pedal confirm that everything agrees. If it sees a mismatch, it goes into a limp mode that limits power to avoid unwanted acceleration.

The P2104 code is not the cause itself. It is the computer reacting to another fault in the system: an inconsistent position sensor, a throttle motor that does not respond, or a problem with the pedal. That is why the first step is to read the rest of the codes.

Dirt in the throttle body, corroded connectors and low battery voltage cause a good share of these cases.

P2104 code symptoms

• Check engine light or electronic throttle control light on.
• The engine stays at idle even when you press the gas pedal.
• Very slow or no throttle response.
• The engine may stall or not get past idle.

Likely causes of the P2104 code

1. Another throttle or pedal code that triggered the protection. Resolve it first.
2. Dirty throttle body. The plate does not follow the command.
3. Throttle or pedal connector with corrosion or loose pins.
4. Low battery voltage or poor grounds.
5. Brake pedal switch or sensor, if it reports the brake as pressed at the same time as the gas pedal.

How to diagnose the P2104 code step by step

1. Read all the codes and start with the ones for position sensors or the throttle motor.
2. Look at live data. Compare the commanded position with the real position and check the two pedal signals.
3. Clean the throttle body with the key off, and do not force the plate by hand.
4. Check the battery and grounds. The voltage should be above 12.4 V at rest.
5. Inspect the connectors at the throttle and the pedal.
6. Run the throttle relearn with the scan tool or the manufacturer procedure.

How to fix the P2104 code

• Resolve the code that triggered the protection.
• Clean or replace the throttle body.
• Repair the connectors and grounds.
• Run the idle position relearn.
• Clear the codes and check the throttle response.

Technical reference data

• Throttle motor: typical resistance of 1 to 5 ohms, driven by PWM with reversible polarity.
• Position sensors: two signals, often one rising and one falling, that must add up to a constant value.
• After cleaning or replacing the throttle body, the idle position usually has to be relearned.
• These are general reference values, so check the manufacturer data for your vehicle.

Brand-specific notes

This system is everywhere. Chevrolet, Ford, Nissan, Toyota, Hyundai, Kia, Volkswagen and Renault use it on almost all of their current gasoline engines. Dirt in the throttle body is the most repeated cause on these vehicles.

A forced idle event is the computer protecting you, so do not just clear the code and drive on. Find the code that came with it.

Frequently asked questions about P2104