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Discussion Starter · #1 ·
Hello all, new member, so my oil temp gauge seems to be acting funny, sometimes my temp will read completely normal, right at a hair below 250° but lately now it will just not rise up at all and sit directly at a quarter on the gauge, so halfway to 250, when this happens the cooling fan just will start blowing nonstop all the time but when the gauge is working as normal then the fan doesn't blow like that, just works normal. What is happening, I am thinking I have a bad oil temp sensor but last time I was at the shop they said there were no codes for it although they strike me as fishy, does this sound like the temp sensor going out? Any help is greatly appreciated.
 

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Munich Mark - 2014 535XD
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1,474 Posts
More info please…

Year, Type of Car / Engine and Miles as a start…

Outside Air Temp ?

Let me do a SWAG, F10 535i approaching 100K Miles ? (from the tags ;-)
 

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Discussion Starter · #3 ·
2011 f10 535i bout 135,000 miles now but I've had her since 40 and she's been great, haven't had to do a lot but change my oil on time, outside temp doesn't matter at all, when it goes to quarter way up, it's sits at the quarter, doesn't move or fluctuate one but, when it's working proper it stays a bit under 250 for the most part, just the straight 6 turbo rear wheel base
 

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Discussion Starter · #4 ·
It's pretty much like the oil temp gauge is just stuck there not working, oh and It has a brand new water pump, thermostat and a radiator that's maybe a year old, I got the new temp sensor too but it was an afterthought really and was the cheap 20 dollar one so I was thinking it might be fritzing.
 

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Munich Mark - 2014 535XD
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1,474 Posts
Thought was on the WP or related but it’s fairly new…

I’d just monitor for now, lookup any codes and eventually check the resistance of the Oil Temp Bulb to see if it is that simple.
 

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You can use this information to test your sensor.


Engine oil temperature sensor
The engine oil temperature sensor is screwed into the main oil duct.
The engine oil temperature sensor converts the temperature of the engine oil into an electrical value (resistance). To do this, a resistance with negative temperature coefficient (NTC) is used. The oil temperature is the measured variable for the following calculations, for example: Fuel injection rate and nominal idle speed.
Functional description
A temperature-dependent electrical resistor is used for temperature sensing. The circuit contains a voltage divider where the resistance can be measured depending on the temperature. A temperature is converted using a characteristic curve specific to the sensor. An NTC resistor (NTC) is installed in the engine oil temperature sensor, whose resistance value drops when the temperature increases.


IndexExplanationIndexExplanation
1Engine oil temperature sensor2two‐pin plug connection
The change in resistance between 217 kΩ to 37 Ω is temperature-dependent and corresponds to temperatures between -55 °C and 155 °C.

Structure and inner electrical connection
The engine oil temperature sensor is connected via a 2-pin plug connection.


IndexExplanation
1Engine oil temperature sensor
Pin assignments

PinExplanation
SIGEngine oil temperature sensor signal
Terminal 31ETerminal 31, electronics earth (ground)
Characteristic curve and setpoint values
Via a signal line, the engine oil temperature information is transferred to the engine control. The engine oil temperature is used to calculate the fuel injection rate and the nominal idle speed.

The engine oil temperature sensor delivers a signal that can be evaluated by the engine control very quickly after the engine is started.


IndexExplanationIndexExplanation
1Resistance2Characteristic curve
3Temperature range
Observe the following setpoint values for the engine oil temperature sensor:

VariableValue
Signal voltage0.1 to 3.3 V
Maximum load current1 mA
Response timeLess than 15 s
Temperature range-40 °C to 150 °C
Diagnosis instructions
Failure of the component

If the engine oil temperature sensor fails, the following behaviour can be expected:
  • Fault entry in the engine control unit
  • Substitute value of oil condition sensor or oil-level sensor (engine-dependent)
General notes
Diagnosis of the oil pressure switch runs within 8 seconds after stopping the engine.
 
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