1995 Chevy S-10 Check engine light and sensors

I just bought my truck a few weeks ago and it was running great then I went in the mud with it and had to change the spark plugs and a sensor on the passenger side right by the exhaust manifold got snapped off it still goes in but I dont know what its called to get a new one and now my check engine light comes on when the gas gauge gets into the red and sometimes shuts off when it goes over a quarter tank and I dont know if it is because of the sensor or not I was told that my water pump was going and that might be why too also ever since I got the truck it uses antifreeze it slowly drains out drop by drop my radiator and the coolant container and by the morning my radiator and container are empty I was told my water pump was going bad is this true