{"nhtsa_id":617850,"type":"service_bulletin","type_name":"Service bulletin","date_added":"2001-04-02","date":"2001-01-01","document_id":"SF220AB","mfr_campaign":null,"replaces":null,"component":"ENGINE AND ENGINE COOLING:ENGINE:GASOLINE","mfr_system":null,"summary":"FREIGHTLINER LLC, ON BEHALF OF ITS FREIGHTLINER TRUCKS DIVISION, IS INITIATING FIELD SERVICE CAMPAIGN SF220AB TO MODIFY THE VEHICLES MENTIONED ABOVE. ADDING AN EXHAUST ORIFICE TO THE INLET SIDE OF THE MUFFLER TO CUMMINS B5.9 AND C8.3 NATURAL GAS POWERED ENGINES WILL ALLOW THE ENGINES TO REACH MAXIMUM POTENTIAL POWER. BY INSTALLING THIS ORIFICE, THE EXHAUST BACK PRESSURE IS INCREASED WHICH ALLOWS THE OXYGEN SENSOR TO PROVIDE THE CORRECT INPUT TO THE AIR / FUEL MIXTURE CONTROLLER. THE MODIFICATION CONSISTS OF INSTALLING AN ORIFICE PIPE AND CLAMP. *TT","document":null,"url":"https://open.wenmarpro.com/bulletins/617850","components":[{"id":"engine","name":"Engine","parent":null}],"codes":[],"topics":[],"vehicles":[{"make":"FREIGHTLINER","model":"FLD","year_from":null,"year_to":null,"match":null,"vehicle_ids":[]},{"make":"FREIGHTLINER","model":"FLN","year_from":null,"year_to":null,"match":null,"vehicle_ids":[]}],"as_of":"2026-10-19","note":"A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.","attribution":[]}