[Joe54yzk]

So lately I’ve had coolant temperature warning and limp mode

I’ll explain the situation
While driving and monitoring the temperature in the hidden menu for more than an hour or so the temps would be between (87c and 95c)

then the temp suddenly would spike in a matter of 1 second to 125c and go into limp mode then i would restart the car and the temp would be 95c and i would drive for another hour with everything running fine

I tested the water pump and it is working, any one had a similar issue?

[marvinstockman]

Your temp sensor might be 'funny'. Are you losing cooling, as an exhaust bubble leaking into the cooling system will cause temps to spike.

Get an infrared thermometer and measure radiator and block temps.

https://www.amazon.com/Etekcity-Lase...zcF9hdGY&psc=1

You can also use it to check for dragging brakes, and air leaks in your home!

[Joe54yzk]

I checked the coolant and it is all there I don’t think a single drop leaked and it is not oily or anything but I’ll order the thermometer and check the temps, but from my knowledge when I opened the hood it wasn’t anything out of the normal heat, i had a 328i that would actually overheat I remember how scorching hot everything was and the smell

[marvinstockman]

It may just be the temp sensor, but be careful as these cars may have more than one temp sensor.

[Joe54yzk]

I put new coolant in the tank and drove it around the city for more than an hour and temps were between 89-93 didn’t get that coolant temperature warning, could it be that low/old coolant caused the water pump to speed up and shut down?

[chaltau]

Check if you have codes related to water pump. It might be in early stages of malfunctioning. It is a 3 (or 4?) speed pump and may be failing at high speed when car is hot causing the temperature to shoot up.

[Joe54yzk]

I checked there was a speed deviation code, im gonna drive it a couple of time while monitoring the temps

[SlowE92]

Definitely a faulty sensor of some sort. You're not going to jump 50 degrees in temperature instantaneously.

[The Nightman]

Originally Posted by chaltau

Check if you have codes related to water pump. It might be in early stages of malfunctioning. It is a 3 (or 4?) speed pump and may be failing at high speed when car is hot causing the temperature to shoot up.

This. The electronics in the water pump can go bad in all sorts of weird ways, but they generally through fault codes before they fail completely.

I would expect a faulty coolant temperature sensor to also throw a fault code, but those are cheap and easy enough to replace if you want to rule it out.

Did you test the water pump by initiating the bleed procedure? You'd want to rule out any air in the system as well.

[crashoverride]

these have electronic water pumps and electronic thermostats which if one is failing the other needs replacing as well. You didn't mention mileage but with this car the waterpump is a known weakness and it's not a matter of "if" but "when" it needs replacing.

coolant mix ratio wouldn't cause a jump. As the thermostat is simple a dumb when too hot open when too cold close. But somehow that process isn't working right.

Start budgeting. it's going to be a thousand or so to replace. Highly recommended to replace hoses while you are down there as well.