2013 bmw 320i xDrive thermostat malfunction symptoms

[328 Power 04]

In ISTA, what is the reported integration level (iLevel, etc)? This is the software version and updates of the car.

My newer 3 series has a purely mechanical thermostat, so I can't compare.

[bmwdirtracer]

No Mark, that's NEGATIVE 1000 degrees.

Now, it's important to note that all automotive temperature sensors are "negative coefficient thermistors". The coldest any of them can realistically read is somewhere near negative 40, and a value near this should also be their failure reading. a false full-negative reading is almost always caused by an open circuit.

Let's take a possible "for instance":

The ECT sensor has a loose connection, or not-quite clean pins. Above zero, the connection is fine, but below that, well, everything shrinks too much....you know how that happens, when it's cold? All of a sudden, the DME sees an open circuit, negative umptillion degrees.....and it knows that SOMETHING is wrong with the reading, because the Intake Air Temp says it's a balmy negative 2. Now the DME goes into emergency mode, and turns the fan on full blast, when it's already plenty cold enough to freeze the balls off a brass monkey. And it sends the water pump into full tilt, and the engine gets really damned cold.

If you brought the car to me with these symptoms, I'd ask you to keep it overnight when it's expected to get bitterly cold, so I could watch live data for ECT and other relevant data. And I'd clean the ECT electrical connector with Wurth Contact Cleaner Oil.

[x3L2004]

No Mark, that's NEGATIVE 1000 degrees.

Now, it's important to note that all automotive temperature sensors are "negative coefficient thermistors". The coldest any of them can realistically read is somewhere near negative 40, and a value near this should also be their failure reading. a false full-negative reading is almost always caused by an open circuit.

Let's take a possible "for instance":

The ECT sensor has a loose connection, or not-quite clean pins. Above zero, the connection is fine, but below that, well, everything shrinks too much....you know how that happens, when it's cold? All of a sudden, the DME sees an open circuit, negative umptillion degrees.....and it knows that SOMETHING is wrong with the reading, because the Intake Air Temp says it's a balmy negative 2. Now the DME goes into emergency mode, and turns the fan on full blast, when it's already plenty cold enough to freeze the balls off a brass monkey. And it sends the water pump into full tilt, and the engine gets really damned cold.

If you brought the car to me with these symptoms, I'd ask you to keep it overnight when it's expected to get bitterly cold, so I could watch live data for ECT and other relevant data. And I'd clean the ECT electrical connector with Wurth Contact Cleaner Oil.

Hey Chris just thought of something. Does this sensor have anything to do with the oil temperature reading ? Cause my car has the oil temperature gauge on the dash and it takes forever (in driving time ) for the gauge to move sometimes it never even moves. If this sensor is responsible for oil temperature readings then I have a feeling my sensor or the wiring associated with is damaged.


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[bmwdirtracer]

Oil takes longer to heat up than coolant. If the engine coolant is way too cold, oil temp may not get to where it should be either. You need to chase the coolant temp issue first.

[BostonDanMI]

Ok, not sure about the engine lagging at 100 kmh, but I had an issue with my 2011 328xi where my radiator sprung a leak, so I had it replaced. When I drove the car after having the radiator replaced, the car would not get to operating temperature (this was wintertime in Michigan). I had also had my thermostat and water pump replaced, due to running the car with low coolant from the initial radiator leak.

Come to find out that there is an internal thermostat for regulating coolant to the transmission in the radiator, separate from the usual thermostat on the front passenger side of the engine compartment. Once I had the radiator replaced a second time, I had heat. Not sure of the other symptoms, but one way to check is to look at the message boards about clamping coolant hoses and driving on the highway, or putting a piece of cardboard in front of the radiator and driving to see if the car comes up to temp.

Good luck.

Cheers,
B.D.

[x3L2004]

Ok, not sure about the engine lagging at 100 kmh, but I had an issue with my 2011 328xi where my radiator sprung a leak, so I had it replaced. When I drove the car after having the radiator replaced, the car would not get to operating temperature (this was wintertime in Michigan). I had also had my thermostat and water pump replaced, due to running the car with low coolant from the initial radiator leak.

Come to find out that there is an internal thermostat for regulating coolant to the transmission in the radiator, separate from the usual thermostat on the front passenger side of the engine compartment. Once I had the radiator replaced a second time, I had heat. Not sure of the other symptoms, but one way to check is to look at the message boards about clamping coolant hoses and driving on the highway, or putting a piece of cardboard in front of the radiator and driving to see if the car comes up to temp.

Good luck.

Cheers,
B.D.

My first mechanic suggested me to change the thermostat mounted on the radiator for transmission cooling (called a heat exchanger or transmission oil cooler or something). But this is the same mechanic who replaced my thermostat three times in a row so I took his call on this very lightly. He said it’s the only other thermostat.


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[x3L2004]

Ok so today is -12.5 degrees and I have loss of engine power above 60 km/h. check engine light on. Fan is on full blast. There seems to be heat in the cabin coming in no issues there ...


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[x3L2004]

Update: so the fix was the coolant sensor or the engine temperature sensor whatever it’s called. A $20 piece. 2 minutes to replace almost plug n play. Stupid previous mechanic cost me $600 changing everything but the little sensor. These fools shouldn’t call themselves mechanics who starts off with the most expensive item and goes down to the cheapest. And if he knew how to read the goddamn reader properly and understood the sequence of events like my current mechanic did it would have saved me hundreds of dollars and 5 fewer trips to the shop. I literally came in to my new mechanic, popped in the ISTA reader and took a look at the log file. Engine temperature repeatedly reporting -1000 degrees Celsius how do you go and change a thermostat when it’s the instrument SENSING the temperature that’s at fault. Good thing I left him he was gonna change the transmission coolant sensor as well. Jeez I’m so pissed off now. Anyways rant over sorry guys thanks for all your help I appreciate it


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