What is a diverter valve? A diverter valve (DV) is a pathway for boost when it is not being used by your engine. Whenever the throttle body is closed, like during shifts or deceleration, the boost needs an escape route. If the boost cannot escape during these times, it can back up and cause shocks to the turbo. These shocks will stall the turbo, slowing boost production upon re-acceleration (turbo lag). Even worse, these shocks can cause damage to the turbo. The diverter valve's job is to open when the throttle body is closing or closed, and reroute the boost to the low pressure intake side of the turbo, where it can do no harm.