Mopar 4669869AD Vapor Canister

The evaporative emissions control system prevents fuel vapors from escaping into the atmosphere by storing them in a charcoal canister. The Powertrain Control Module (PCM) monitors the system and draws vapors into the intake manifold when the engine is at normal temperature. A strong fuel odor or fuel leak from the canister indicates a fault in the system, especially in hot temperatures. The system is pressurized by a Leak Detection Pump (LDP). If a leak causes pressure loss, the PCM stores a fault code and triggers the CHECK ENGINE light. A loose gas cap is a common cause of pressure loss.