Went for an emissions test and car failed for a P1850 code. I was baffled because I just installed a gm rebuilt unit 3 weeks earlier. Ran test at a friend'* shop and everything tested out fine. Went back and it failed again. Ticked off, I let the car sit for a month. I decided that I needed to start the car because of really cold weather. Bummer cause the windshield steamed up and antifreeze puddles the floor. Bought and installed New heater core. P1850 code gone. It appears that the hidden leak allowed the fluid to heat enough to throw the code. Problem fixed and running like an SE Supercharged should.

SE'* aren't supercharged. Did you make a swap?

It was optional for 96 and 97.

I am having trouble, is that an EGR flow high code?

To clarify, it was optional for more years before that, but 97 seems to be the last year, and it'* a pretty rare option.