Evaporative Emission (EVAP) System

WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2003 Lexus SC 430, 2003 Lexus RX 300, 2003 Lexus LX 470, 2003 Lexus LS 430, and 2003 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Pressure switching valve Vacuum Switching Valve (VSV) is also known as vapor pressure sensor Vacuum Switching Valve (VSV).

The EVAP system prevents fuel tank gasoline vapors from escaping into atmosphere. Fuel tank gasoline vapors are routed through EVAP canister into intake manifold for combustion in cylinders.

The Engine Control Module (ECM) monitors fuel tank pressure to determine if a leak or an abnormality exists in EVAP system. A pressure switching valve Vacuum Switching Valve (VSV) is located in vapor line to EVAP canister. A canister closed valve (CCV) with VSV is located between EVAP canister and air intake system (except LX470). ECM will operate pressure switching valve VSV and canister closed valve VSV (if applicable), while vapor pressure sensor monitors fuel tank pressure and EVAP system. Vapor pressure sensor delivers an input signal to ECM to indicate fuel tank pressure. If a leak or an abnormality exists in EVAP system, a diagnostic trouble code will be stored in ECM.

An EVAP Vacuum Switching Valve (VSV) is used to control EVAP system. ECM operates EVAP VSV which controls vacuum flow for EVAP operation. For EVAP system testing and component locations, see EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article.