I've already replaced the ambient sensor and the damn thing still doesn't read anything just shows ---
Any ideas? TIA

 

possibly your cluster? Was the wiring near the sensor ok and not corroded or damaged?

 

I had the same problem, lasted for a few months and then one day I start my car and its working again and has been working ever since.

Still not sure what caused it to malfunction, maybe yours will come back like mine did.