Stopping the Chevy Brake Booster Vacuum Leak
This bulletin applies to 2015-2021 Chevy Colorado vehicles. The brake booster may have a vacuum leak, possible hiss noise and/or DTC C0299 stored in the ECM. This is possibly caused by the vacuum pump leaking oil into the booster.
Inspect inside the vacuum hose and booster for a sticky-feeling substance on the rubber. If this is present, this is a likely indication that the vacuum pump is leaking oil. Replace the pump and hose along with the booster if needed.