What is the reason for unstable idle speed after cleaning the throttle body of the new X-Trail?

[VonCollin]

New X-Trail's unstable idle speed after cleaning the throttle body is caused by the throttle opening not being reset. Due to long-term carbon buildup, the carbon deposits squeeze the throttle body, causing its opening to expand accordingly. After cleaning the throttle body, if it is not reset and the throttle opening remains in the pre-carbon buildup state, it will lead to increased air intake, and in severe cases, unstable idle speed may occur. Computer reset of throttle opening: Most modern cars use electronic throttle bodies, which require a diagnostic tool to match the computer for throttle initialization to achieve normal idle speed. Some older models still use mechanical cable-operated throttle bodies, and these vehicles will gradually restore the throttle opening to the initialized state during subsequent driving. Manual reset of throttle body: Before cleaning the throttle body, disconnect the negative terminal of the battery, or after cleaning, turn the key to the ON position and wait for a few minutes before turning it off. Then turn it to the ON position again, press the accelerator pedal fully without starting the engine, and then start the engine.