NTK AFRM Replacement Sensor (SNSR-01006) About this sensor: The new NTK AFRM (Air Fuel Ratio Monitor) system debuted in 2014 with a completely new sensor architecture, the ZFAS-U2. Unfortunately, the new ZFAS-U2 replacement sensor has been unavailable while the NTK AFRM has been selling for many months. We have had frequent customer requests for replacement sensors while NTK has not yet provided the replacement. Ballenger Motorsports is happy to present the replacement sensor for the NTK AFRM (SNSR-01005)! NTK Part Number: UAR0004-EE001 NTK Stock Number: 91091 The Ballenger Motorsports AFR500 - Air Fuel Ratio Monitor Kit - Wideband O2 System is also available (SNSR-000990) on our website, eBay, & Amazon. The AFR500 makes true wideband technology with top of the line measurement equipment available to enthusiasts and tuners for the first time. Air fuel ratio offers critical feedback for tuners to alter parameters to achieve maximum power and efficiency from their engine.