Sensors Table 1-4 Sensors Component abbreviation Component name NPLED Media sensor SR1 Yellow drum home position sensor SR2 Magenta drum home position sensor SR3 Cyan drum home position sensor SR4 Black drum home position sensor SR5 Fuser delivery sensor SR6 Output bin full sensor SR7 Fuser pressure release sensor SR8 MP-tray-media-presence sensor SR9 Primary-transfer-roller disengagement sensor SR10 New ITB sensor SR11 Developer alienation sensor SR14 Loop sensor 1 SR15 Loop sensor 2 SR20 TOP (top of page) sensor SR22 Duplex re-pickup sensor (HP Color LaserJet CP4525dn, HP Color LaserJet CP4025dn, and HP Color LaserJet CP4525xh only) SR23 Tray 2 paper surface 1 sensor SR24 Tray 2 paper surface 2 sensor SR25 Tray 2 paper present sensor RD sensor Environment sensor (temperature and humidity) Yellow toner-level sensor Magenta toner-level sensor Cyan toner-level sensor Black toner-level sensor Residual toner full sensor TH4 Laser scanner temperature sensor ENWW Engine-control system 7