Ocelot13

Back at the end of March (around 110k miles) my water pump died, garage replaced water pump and thermostat housing. No issues up until a few days ago. My yellow and red over heat messages came on my idrive and dash and immediately went away. Didn't do it for a few days, now it's doing it pretty often, but never stays on. Dings, goes away, very intermittent. I did the bleed cycle and my water pump was pumping, used inpa to test the fans and water pump.. all good. I did have a water pump error but I thought it might have been from when the pump died before. Today when driving, my normal temp was around 200F, and when the error would come on, the temp would be around 170F, then after the error was off, the temp would rise back up. Is my pump just becoming intermittent? Allowing the fluid in the radiator to drop in temp and fluid in the engine to get to hot before the pump decided to kick on and pump the hot fluid out?

FormerE30Owner

Or thermostat problems. And, perhaps, a temperature sensor problem. I would think the sensor.

Ocelot13

Which sensor would it be? I'm still getting the temp reading over an obd reader to torque pro on my phone, the fans are kicking on (not to mention when the message comes on, the temp is below normal operating temp)

seanjordan20

It seems the thermostat is being stuck open to me

Ocelot13

Wouldn't that let the fluid stay moving and not be kicking the over heat message on?

seanjordan20

Yes that would but you stated it went down to 170 giving the results of and open termo. Why would it give you that message when the temp was at 170 I don't know. That would only warrant no heat. If it is giving you conflicting information then that would be a sensor issue. Meaning it's on its way out. At this point you have to troubleshoot to see what the issue is. When it gives you the message see if the temp is correct. If it is correct then your sensor is not the issue and move on to the pump. There are only a few parts that control water flow. Thermostat, sensor, and Pump. The parts in between are mediums which assists the flow. Check to see if you are getting any more errors in INPA on the pump. What brand pump was put in. The way you are explaining it after I read it again point to a faulty sensor.

Ocelot13

The last time I got the message, I had my Obd scanner in and that's when the temp was saying around 170° or so. It's just so random and that makes it hard to diagnose. I do have inpa and was able to test my fan with that so I know the fan is good. Tomorrow after I get up, in gonna use inpa to run the water pump and check the stream compared to when doing it with the bleeding process. It seems to pump fine during the bleed process (I assume the pump is supposed to cycle some during it).
so.
Over heat message randomly, and typically just for a split second, sometimes it'll ding on and off a few times.
Fan works, tested with AC and with inpa
Pump does work, tested with bleed process.
Over heat message came on with low temps, such as ~170°F.
Pump and thermostat was replaced at end of March.

seanjordan20

The problem you are having would frustrate the hell out of me. It's not making any since. It's real hard to say without me being there. My next step would be just changing the sensor that triggers the error since it's cheap and a fairly easy DIY to see if that makes a difference. Try unplugging your battery for 15 mins maybe that will reset something if everything is checking out good but clear all codes prior to. Just throwing something out there.

seanjordan20

Just thought of something. What year and model do you have.

Ocelot13

It's an 07 525xi.

Went and got a new sensor today (the one that goes in the front of the engine at the top. Driving there and back was mostly highway, probably about 50 miles round trip..never got any lights, obd temp readout was typically between 195-210, ran like a champ. Got home, let it cool down, swapped the sensor anyways, and just went on probably a 40 minute drive on back roads...still never got any messages to come on. I hate how random it is