What does code P0120 mean on a 1998 Mazda Protege?

Code P0120 on a 1998 Mazda Protege indicates a problem with the throttle position sensor (TPS) circuit. This code typically means that the engine control module (ECM) has detected an abnormal voltage reading from the TPS, which can affect engine performance and throttle response. Possible causes include a faulty TPS, wiring issues, or poor connections in the circuit. It's advisable to inspect the sensor and its connections to diagnose and resolve the issue.