Leak Detection Pump (LDP) EVAP System

WARNING: This page is about a different car, the 2010 Audi Q7, 2009 Audi Q7, 2008 Audi Q7, and 2007 Audi Q7. However, it is still accessible from the selected car via links, so may be relevant.

The leak detection pump (LDP) is integrated into the EVAP system and can have two functions. The LDP can:

Pressurize the EVAP system and detect a drop in pressure that would indicate a leak.
Function as the EVAP Canister Vent on vehicles that do not have a separate EVAP Canister Vent.

The LDP is a vacuum-driven, ECM controlled, diaphragm pump. In order to operate, the engine must be running and vacuum applied to the Vacuum Switch.