OBD-II code P2621 indicates that the powertrain control module (PCM) has detected a low voltage condition in the throttle position output circuit. This circuit is responsible for sending the actual throttle blade position signal back to the PCM. A low voltage reading typically points to an electrical fault in the sensor, wiring, or connections rather than a mechanical throttle issue.
The sensor itself, often integrated into the throttle body assembly, can fail internally and output a low voltage signal to the PCM.
The signal wire between the throttle position sensor and the PCM can become chafed, shorted to ground, or broken, causing the voltage to drop.
Moisture intrusion, bent pins, or a poor physical connection at the throttle body can disrupt the signal voltage.
If the sensor lacks a proper ground, the reference voltage and output signal can become skewed or drop too low.
In rare cases, an internal failure within the PCM prevents it from reading the throttle position voltage correctly.
It is not recommended. The vehicle may enter reduced power or limp mode, and stalling can occur, making it unsafe to drive in traffic.
Yes, a failing throttle position sensor or integrated throttle body assembly is a very common cause, as the internal electronics can fail and output a low voltage signal.
The code may clear temporarily if the condition is intermittent, but it will return if the underlying electrical fault is still present.
No, replacing the PCM is rarely the correct fix. Drivers are often incorrectly told to replace the computer, but the issue is almost always a failed sensor, damaged wiring, or a bad connection.