EPA 2017-2025 regulations have increased the corporate average fuel economy (CAFE) requirement by 33% for 2025 model year vehicles. Similarly, the EU has set a target of reducing CO2 emission by 27% (with respect to 2015 targets) for vehicles launching after 2021. These constraints have diverted the attention of most of the OEMs towards hybrid electric vehicles, which give out lower emissions and have higher fuel economy as compared to the vehicles propelled by an IC engine. Hence, many automakers have started working on plug-in hybrid electric (PHEV) variants of the existing vehicle models.Vehicle architecture of a PHEV consists of additional electrical components apart from the conventional coolant consumers. The coolant flow requirements to all these additional components becomes challenging for its efficient operation and coolant flow balancing.The scope of current work is to simulate the PHEV coolant system to visualize flow distribution to all coolant consumers in the vehicle, in a one-dimensional (1D) environment using FloMASTER®. The 1D coolant network model is validated with available vehicle test data. Transient simulations are also performed to mimic the actual driving conditions by using standard test cycles. Good correlation is obtained with the test data with deviations well under 10% from the test values.