Low Coolant Temperatures


New Member
Hi everybody, I've been having some odd temperature readings beginning a few weeks ago. Did my routine maintenance to get the bike ready for the season, but also changed the coolant since its quite old. Never had an issue with the temperature since I've owned it the past 3 years. It is an 09 with 13k miles.

During my first ride, I noticed that the temperature was jumping around from 160 to 162, 167, down to 160, etc. Every so often it would randomly change to a "normal" operating temp to around 170-180 region. It's all over the place. Figured maybe I still have air in the system, so I took the radiator cap off and ran it for a few minutes. Saw some small bubbles, but it is still having the temperature issue.

I started it up with the cap off and it looks like the thermostat would open because the fluid level dropped once the temp was around 170 degrees. The reading went straight from 170 to 160 and it stayed there. Anytime its idling for a long period, it should get up to 205 and then the fans kick on (vcyclenut reflash), which it doesn't do now.

Do you think this would be a faulty coolant temp sensor? I can take that out and check that. Some people mentioned a procedure for checking the resistance or something. I could take it out and put it in a bath of water at a known temperature and check it that way. Any ideas?