A monitoring unit wirelessly monitors sensor(s) associated with a vehicle and includes (a) a radio frequency (RF) receiver that receives RF signals from one or more sensors; (b) a processing unit connected to the RF receiver that monitors information related received RF signals from the sensor(s); (c) the processing unit monitoring the received RF signals and a status of an output of the sensor(s) associated with the vehicle. The received RF signals may include information on a value of an output of the sensor and limits of acceptable values, and the processing unit generates an alarm when the value of the output is outside of the limits of acceptable values. The alarm may be a visual indication visible from the exterior of the vehicle.