What is the problem when a car revs by itself without stepping on the accelerator?

[MiguelFitz]

When a car revs by itself without stepping on the accelerator, it is mostly due to an issue with the idle motor. It is recommended to check the idle motor and clean the throttle body at the same time. If the car revs on its own without pressing the accelerator, the cause should be analyzed based on different situations. For electronic throttle systems, focus on checking the throttle and accelerator pedal. For cable-operated throttles, inspect the throttle cable and idle motor. Throttle issue: The throttle cable may not be returning properly, possibly due to insufficient lubrication. Solution: Remove the cable, pour lubricating oil from the upper end of the cable, and allow the oil to slowly penetrate into the cable tube. Idle motor problem. For example, the idle motor may be stuck or have lost its memory. Solution: Clean or replace it and then recalibrate. This requires initialization using a diagnostic computer.