1996-2005 Suzuki DF40, DF50 Four Stroke Outboard Service Manual, Page 48Get this manual
PERIODIC MAINTENANCE 2-22 2Remove grommet and stbd.lower side cover(See page 7-1)
3Remove plug from oil pump case and install the O2 sensor and protector sleeve 418213-74F00O2 sensor 18498-90J20Protector sleeve