I just replace a broken vaccum line that was connected from the brake booster to the engine which cause all sort of problems including the check engine light to come, All the other issue are resolve but the check engine light will not turn off. Did i miss a step during the installation or maybe it will go away in a couple of days?

 

it will only switch of by a scanin tool or mb diag tool

 

You might try leaving the battery leads off for a night. The check engine light should go out once the ECU clears it's memory. Provided you've solved the problem it shouldn't come back on. Hope this helps.