P2104 indicates that the engine computer has detected a malfunction in the electronic throttle control system and has forced the throttle plate to remain at idle as a fail-safe measure. This prevents uncontrolled acceleration but severely limits vehicle operation, often referred to as limp mode.
Carbon buildup around the throttle plate restricts movement, causing the actuator motor to struggle and triggering the forced idle fail-safe.
Corroded, loose, or damaged wiring and connectors in the throttle actuator circuit disrupt the signal between the throttle body and the engine computer.
Erratic or out-of-range signals from the throttle position or accelerator pedal sensors cause the computer to lose accurate track of throttle position, initiating limp mode.
Significant unmetered air entering the engine can disrupt idle adaptations and cause the throttle system to fail its rationality checks.
The engine computer has a failed internal driver for the throttle actuator, though this is extremely rare compared to external component failures.
It is not recommended. The vehicle will likely be stuck in limp mode with no throttle response, making it unsafe for normal driving and only suitable for moving off the roadway to a safe location.
Yes, this is one of the most common causes. Carbon buildup prevents the throttle plate from moving smoothly, forcing the computer to lock it at idle to prevent a runaway engine condition.
Rarely. Mechanics often misdiagnose this code as a PCM failure, but the computer is almost always doing its job correctly by forcing idle due to a mechanical or electrical issue at the throttle body. Replacing the PCM should be an absolute last resort after all wiring and sensors are verified.