This document defines the procedures for assessing the performance of PEMS equipment, which is used for the on-road measurement of tailpipe emissions of light-duty vehicles, on the basis of a common test procedure that simulates the range of conditions experienced during on-road tests. This document prescribes: a) the tests to be conducted, and, b) a procedure to determine, for any particular piece of PEMS equipment, an appropriate uncertainty margin to reflect its performance over those conditions. The key test variables are as follows (but not limited to the ones mentioned): 1) temperature, humidity and pressure and step-wise or gradual changes, 2) acceleration and deceleration (longitudinal and lateral), 3) vibration, inclination and shock tests, 4) instrument positioning on a vehicle, 5) combinations of (1) to (4), 6) cross-Interferences, 7) signal-processing, data treatment and time alignment, and 8) calculation methods (excluding the regulatory post-processing of data).