I am using the @RBoy custom DTH for the monoprice 4 in 1 sensor and I am going through the 2 AAA batteries in about a week or 2. Anyone else having battery issues with this sensor?
Do a factory reset on the sensor (see manual). Usually that resolves it. Also it may help to add a repeater close by to reduce the radio power levels. If that doesn’t solve it you may want to contact Monoprice for a replacement. The electronics may be bad. Also assuming that you’re using Alkaline or Lithium 1.5v AAA batteries not rechargeables.