Description: Silverado, Sierra 2500 HD. Gas. Front. Silverado, Sierra 3500 HD. This part requires programming and/or special setup procedures. GM Service Information describes the procedures and special tools needed to ensure proper operation in the vehicle Detects oxygen content in the exhaust gases to help optimize emissions This GM Genuine Part is designed, engineered, and tested to rigorous standards and is backed by General Motors

Description: Controls fresh air flow to the canister Sends fuel vapors to the engine for re-burn Helps control fuel tank pressure