Q: I have a 2013 Honda fit with about 20k miles. Sometimes the check engine light turns on with code p2176 and it will turn back off

Modern vehicles no longer have a mechanical connection from the gas pedal to the engine (accelerator cable). It has been replaced with electronic motors and sensors. Potentiometers on the accelerator pedal send signals to the throttle body actuator. They tell the throttle body actuator how far you have pressed the accelerator pedal and open the throttle the corresponding amount. Over time, something as simple as carbon build-up on the throttle plate can effect the readings. For example, even a small amount of carbon build-up on the throttle plate can prevent it from fully closing. If this happens, the engine control unit may not properly detect when the engine is at idle. Cleaning the throttle body may be a simple fix. If that does not work, then there can be a few other causes. A faulty throttle position sensor, MAP sensor, or even a slight vacuum leak can cause the same symptoms. If a throttle body cleaning does not help, have a certified technician look into the fault code to find the exact cause. replacing parts at random can become expensive as most electronic parts are not returnable once installed.