1996-2005 Suzuki DF40, DF50 Four Stroke Outboard Service Manual, Page 353Get this manual
13-17 DF40DF50 "K1" (01) model
The O2 sensor used for the feedback test procedure must be in proper working order and installed securelyIf either sensor or installation is improper, the feedback operation will be performed incorrectly and could possibly result in engine operating problems
NOTE: The O2 sensor is NOT WATERPROOFCover O2 sensor with the protector sleeve to protect from water spray Cut off the protector (PN 18498-99E40) to length of 20 30 cm (7.8 11.8 inThe O2 sensor must be completely covered as shown