1. A method of diagnosing impulse line plugging for a pressure transmitter, comprising: providing said pressure transmitter including a pressure case and at least one impulse line coupling said pressure transmitter to a fluid pipe or tank having a process fluid therein, said pressure transmitter including a pressure sensor in said pressure case configured to measure a process pressure of said process fluid, a temperature sensor for sensing an ambient temperature, and a processor accessing baseline data for said process pressure and said ambient temperature stored in at least one associated memory, said processor coupled to an output of said pressure sensor to receive said process pressure and to an output of said temperature sensor to receive said ambient temperature and implement an automatic impulse line plugging diagnostic (ILPD) algorithm stored in said associated memory; obtaining process measurements including of said process pressure from said pressure sensor and of said ambient temperature from said temperature sensor; wherein said processor runs said ILPD algorithm implementing: utilizing said process measurements, comparing a magnitude of said process pressure to a baseline pressure predicted from said baseline data corresponding to a magnitude of said ambient temperature, and using results of said comparing to determine whether said impulse line is plugged.