Figure 1-9 Sensors PS4 PS1 PS2 PS225 PS215 PS205 PS8001 PS502 PS3 PS8008 PS451 PS8008 PS451 Table 1-8 Sensors 12 Chapter 1 Theory of operation ENWW Item Description Item Description PS1 Face-up sensor PS225 Media width sensor PS2 Fuser delivery sensor PS502 Duplex media-feed sensor (duplex models only) PS3 Cassette media-presence sensor PS451 Paper feeder cassette media-presence sensor NOTE: PS451 is used in Tray 3, and Tray 4