cooling problem please help
 

I have 2006 BMW 530I N52 engine. My car a problem that it would never fully warm up with the heater on. I would get BMW Code 2EF4 radioator thermostat, mechanic jammed open
Today my mechanic changed it for a new one and while its a little better the problem is still there. With the heater turned off my car warms up fully no problem, but as soon as I turn on the heater my temp goes down to 75C. After changing the thermostat I got an error that said
2E83 Electrical water pump, power-reduced operation dry operation. I cleared the error and it hasnt come back yet. I'm wondering what could be the problem can a bad water pump really cause not enough heat in the engine with the heater on? If I wait till the car is fully warmed and turn on the heater it would start losing temperature about 1C degree per second until it stops at about 75C. Anyone?

You should change the temperature sensors as well. Change the one on the thermostat first, if that doesn't fix it then also change the sensor in the hose bottom of radiator passenger side. If you haven't done the water pump I would go ahead and do that as well if you have substantial miles on the car.

Is there more than 1? Is this one you are talking about? 2006 BMW 530i Engine Coolant Temperature Sensor in Canada - Canada 2006 BMW 530i Engine Coolant Temperature Sensor Which other sensor do I need?

I have 66k miles on the car. The water pump costs almost 700 bucks and I would only change it as a last resort.

Thanks

Yes that looks like it.
Number 4 in this link
RealOEM.com BMW E60 550i Waterpump - Thermostat

and the one on the hose on the left of the water pump, far left in this pic.

RealOEM.com BMW E60 550i Cooling System Water Hoses

Disregard what I said. I just realized you mentioned the 06 530i I think you have a different system, I think you have the electronic water pump. Either way you will have a temperature sensor so try to find it and change it.

Temp sensor [for cooling system] on N52 is located on the lower radiator hose.

Well, I changed both sensors and problem is still there. I changed the one in the radiator hose and the one that goes inside the engine. What else could it be? If the heater or ac are on, engine starts losing temperature like crazy. I really dont know what else to do. Anyone?

It may be that your thermostat was never bad to begin with and you have a wiring harness issue, something which isn't all that uncommon (do a search). Replacing the harness is very expensive so if that's the problem, you may be better off trying to jerry-rig a fix. I guess it's also possible the cooling system wasn't bled properly. Have you tried rerunning the 12-minute bleed procedure again? When you run it do you hear the water pump cycling on and off and can you feel coolant flowing through the hoses? If not, the water pump may be toast. If it's never been replace you're definitely overdue.

Yeah I ran the 12 min bleed procedure twice today just to be sure. Yeah I could hear my pump cylcing on and off and felt the coolant flowing. It made no difference, and there were hardly any air in the system if any. How would I go about troubleshooting wiring harness issue?

Thanks

Sorry, no idea. Check for 12v at the tstat connector?