The AUC sensor is located at the top front of the engine. It’s supposed to sense air pollution.

The secondary water pump does not exist on gas fired E46s. Maybe if you have a diesel car?

The water valve (known as the heater control valve) is controlled by the climate control module in the dashboard. If the car has automatic climate control this module is known as the IHKA. If the car has manual climate control this module is known as the IHKM. Regardless, the IHKA/M controls the heater control valve by sending the valve voltage. The valve is located on the left (intake side of the engine compartment) inner fender. There are 2 smaller hoses attached to the valve. There’s also an electrical connector at the top. Remove the connector to see if the short circuit goes away. If it does then the valve is bad. If it does not go away then you have either a wiring issue or the IHKA/M is bad.

Here’s a link to wiring diagrams: BMW WDS Online.
Click on body then heating and air conditioning.

 

I disconnected both the valve and the water pump. The water pump still said short circuit to negative and the valve didnt show any error. Connected them again, same story, valve short circuit to positive pump to negative. Is there a chance the IHKA could be bad?

 

That’s a possibility.

 

hey update i bought the water pump which is on the same hardware with the valve and the AUC sensor, the valve seems to work but when i turn the AC i hear a hissing sound is it possible that the fan doesnt turn on and if it turns on i guess its really quiet