working on this code 17887 brake boost vacuum system. mechanical failure. check vacuum pump and hoses [ok] any ideas ?
thanks

 

Do the brakes work ok? (Maybe a sensor issue.)
Is it building and maintaining a vacuum?

Rough check for building and holding vacuum:
After the engine has been running and without touching the brakes, slightly crack open the vacuum line to the booster and listen for a sucking sound. If it has a vacuum, Run the car, turn it off and let it sit over night or so. Check vacuum again.