yemff

Can someone explain to me how the egr works. As far as I know egr comes on when the cylinder temp is too high. So what sensor is measuring this temp? as far as I can tell the egr temp sensor measures the temp in the intake manifold. When I read egr temp with vag com it is only around 60C, which seems pretty low if it is measuring cylinder temp. Also when the egr does open how long will it stay open for?

sam.sun

EGR will open usually when the engine is at cut off or at light charge(cruising at low speed) and it will stay on as long as the ecu thinks it should be depending on a lot of things as water temp and so on..