It could be your matrix. Hard to be sure. What did you fit when you say non-genuine?Hi all,
Just joined here as I too have a very similar issue to what's been discussed above.
I've flushed the coolant system completely (with a Forté flush and also connected a hose pipe to the header tank). I've replaced the heater matrix already (non genuine part) and I've removed the header tank with the silica bag in for a new tank. I've also completed a bleed through a diagnostic machine.
Still very intermittent heat, ofter freezing cold when driving but can get warm(ish) when stationary or slow driving.
I've just bought a genuine heater matrix.
Just wanted to see what others think as the garage seems unsure as to what it is. Thanks.
Some people have had other contributory factors such as issues with EGR cooler or pump I think.
Or stick in another matrix and see how you go.