Now that the cold season is coming and will surely have some problems with reaching the operating temperature at the Y25DT by a defective AGR thermostat, I have now finally closed the housing. The closure plug has proved to be not 100% safe – it has moved a piece into the hose, I have removed the “Lyra spring” and removed all parts (thermostat, spring and sleeve) from the housing and the bore of the connection piece with a Z ylinder head screw M6 x 15 and an M6 nut closed. – fits exactly, possibly use a self-locking nut and washers. Be careful when installed – the connector fits only in one position. LG robert