Genuine Gates Engine Cooling Thermostat - TH21689G1. A thermostat is a component that is used to monitor the temperature of a system and ensure it is maintained at a set temperature. A damaged thermostat could potentially mean that the vehicles engine is not running at its optimum temperature causing damage to internal components. This Gates OE Quality Replacement Coolant Thermostat (TH21689G1) is designed to fit Peugeot vehicles. It has an opening temperature of 89°C and comes with housing. Quantity included is 1, sold individually. We are dedicated to customer satisfaction and offer free expert advice and UK mainland shipping.