Lawdog, were u reading my mind? I thought I had the problem solved, installed new O2 yesterday and ran mower for 10 mins, no code, , used it today after a few mins of use check engine light onfelt sick. Still running pretty good but not right, finished day with no problems but not using again till problem solved, dont want to ruin the new O2 sensor. The wire/connection u refer to, is low and attached from lowest part of frame and to started body? I dropped a nut and while looking I saw that connection and was going to check it. Do u recommend removing the connector and replacing with a tinned copper one? Thanks to all for your input, I am going to correct this problem if it is the last thing I do, LOL.