Sometimes the sensor has difficulty connecting or the app says “Poor heart rate signal”. This is usually easy to fix!
• Moisten strap - rinse strap leads (shiny plastic portions) in water before attaching sensor (some prefer spit, but soaking the leads briefly in water should be adequate). If you’re already sweating, that should do the trick.
• Ensure sensor is secured with both snaps.
• Check strap position - see illustration above.
If the above doesn’t seem to be helping, then replace the standard CR2032 coin cell battery.
A new battery should last for several months, even with daily use provided the sensor is disconnected from at least one snap on the strap between uses.