Heart rate monitor (3)

My heart rate monitor (Timex) defaults to 240 regularly. I have tried HR gel but still get the same error. Seems to happen more in cool windy conditions. Does anyone have the same issues and or solutions?
Thanks
M

Mine will show erratic readings when riding if it is chilly out. Once I warm up and get sweat under the strap it settles down.

Other than tightening the strap I don’t know what to suggest if gel doesn’t help.

Same here. 240 often until it / I warm up. Nearly every run my max shows 240 because it’s zoned out for a period. Water on the sensor before you start helps but hasn’t solved the issue.