UKPassats

Hello, now the winter weather is upon us the coolant light has started coming on randomly when driving. I have replaced the inlet manifold thermo-switch and expansion tank and still keeps happening. Temperature gauge works as normal and fan comes on. Next step might be to replace the cooling fan thermo switch on the radiator? I am wondering if there is just an electrical problem somewhere. We ran the diagnostic and nothing comes up.

Any further thoughts greatly appreciated.

1994 1.8CL Estate