I just purchased my first diesel an 02 Silverado Duramax with 128,000. I have been getting a slight coolant odor. I think it is coming from the engine area but I am not sure. I can't see any sign of a leak but I lost some coolant on a 200 mile tow last weekend.

I also started getting a Glow Plug Circuit Performance error (P0380) The truck seems to start fine.

Any advise on finding the coolant leak or solving the P0380 problem would be greatly appreciated. I am hoping that I didn't buy someone else's problem