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Thread: where is the engine temp sensor located?

  1. #1
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    where is the engine temp sensor located?

    hi...

    sometimes my engine temp gauge falls to the cold area and goes back to normal, it's the sensor?

  2. #2
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    sounds like you need to bleed your cooling system; but, it could be the sensor or poor engine grounding.


    the sensor(s) are located in the thermostat housing and radiator.


    http://www.realoem.com/bmw/showparts...17&fg=05&hl=24


    http://www.realoem.com/bmw/showparts...11&fg=35&hl=21
    Last edited by mattmartindrift; 03-23-2010 at 01:38 PM.

  3. #3
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    so what do you suggest? thanks.

  4. #4
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    1) check engine grounds
    2) check coolant level
    3) check connections on temperature sensors.
    4) bleed cooling system

  5. #5
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    where is these engine grounds? you mean to the wires that located on the coils bolts??

  6. #6
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    i believe this button is accessible to everyone, if not:

    http://forums.bimmerforums.com/forum...to_forumsearch

  7. #7
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    i searched and from what i've seen it's on the left wing next to the air filter?

  8. #8
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    http://forums.bimmerforums.com/forum...=Engine+ground

    Karmicly enough, on my drive from home to work (the time between my last post to this one) I had the EXACT problem you describe.


    I forgot to mention - use OBC test 07. The OBC test07 displayed -128*C which indicated to me a faulty sensor. However, when the OBC read a negative temperature, the gauge was pegged to the right.


    So, I pulled over, killed the engine, popped the hood and wiggled the connectors, made sure they were on tightly - I had them off this weekend during some maintenance. Closed the hood, got back in the car, no more issues for the last 30mi. of my commute.


    "How do you perform test 07" you ask. this is how:

    http://forums.bimmerforums.com/forum...&highlight=OBC

  9. #9
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    so if i'm driving and the needle goes to the cold area and i see in the obc that the engine temp is 100c so i need to replace the sensor? and if so, witch one, the one in the radiator or on the termostat?

    thanks!

  10. #10
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    100C is normal, in fact up to around 114C is normal.

    i'd say 120C is a starting point to be alarmed.

    I don't know which sensor to replace, to be honest with you. Perhaps Qsilver can chime in and inform which sensor the gauge cluster uses.

  11. #11
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    but if the obc shows the temp so how could it be that the sensor is not good?

  12. #12
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    that would indicate to me that there are two seperate sensors, or your IKE (cluster) is going bad.


    You are saying that in OBC Test 07 the readout says "KTMP: 100C". While it shows this the needle is in the COLD/BLUE area?

  13. #13
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    no...i didn't tried that yet, but i'm pretty sure that the engine temp is fine because it's impossible that the engine will be cold in a second

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    It's the double temp sensor that you need to replace, but your problem may just be a bad connection.

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    Quote Originally Posted by idan View Post
    no...i didn't tried that yet, but i'm pretty sure that the engine temp is fine because it's impossible that the engine will be cold in a second

    yes, of course it's impossible. your OBC readout tells us your temps are normal.


    16valex, could you elaborate on which sensor that is? radiator or waterpump sensor?

    I have also advocated him checking the sensor connection.

  16. #16
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    Double temp sensor

    Here's the link to the double temp sensor. It's number 9 on the water pump.

    http://www.realoem.com/bmw/showparts...11&fg=35&hl=21

  17. #17
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    Surprised no one Mentioned the Thermostat. Failed T-stat could make your temperature go down on high speeds and return to normal during low speed traffic

    also, check the connections of the temperature sensor, located on top of the WP.
    Last edited by SpeedsterBek; 03-24-2010 at 08:51 PM.
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  18. #18
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    Quote Originally Posted by SpeedsterBek View Post
    Surprised no one Mentioned the Thermostat. Failed T-stat could make your temperature go down on high speeds and return to normal during low speed traffic

    also, check the connections of the temperature sensor, located on top of the WP.


    it's not possible to shed more than 30*C instantaneously, the amount of heat energy in the engine and cooling system make it impossible...hell, even if you removed the sensor from the radiator and stuck it in ice-cold water it would take a few seconds.

  19. #19
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    hi...

    i checked the ground wire and it looks ok, and i looked on both sensors, on the radiator and on the thermostat, and they are connected, what to do guys?

  20. #20
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    did you pull off the plugs and actually look at the connections?

    did you make sure your grounds aren't just connected, but are WELL connected - good metal-to-metal contact?

    have you scanned the car for any error codes, specifically the IKE and/or DME?

  21. #21
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    the ground is very well connected, and i didn't disconnected the sensors, because i don't know how to do it, and i'm afraid to break something, and i didn't scanned the car...

  22. #22
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    On M51D25, 325 tds. from 1996 to 1998 i read that engine coolant sensor is a combined type of sensor? Is this true.. Article here http://www.autozone.com/repairinfo/r...00c152801b20c3

    In that case, is the cylinder heads different or is the holes placed the same way..? Im abut to replace head gasket and cylinder head.. Anybody knows?

    - - - Updated - - -

    I checked with realoem and an 1994 M51 cyl head has the same prod.nr as an 1997 M51 cyl head.

    Before 01/1996 M51 had different sensors for DDE colant temp / and one for coolant temp guage. 2-pol each. After this date bmw replaced them two sensors into one, 4-pol combined DDE coolant/guage coolant.

  23. #23
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    Not many tds from that era (if any) here in the states.
    There is an oil temp and pressure sensor at the base of the oil filter canister as indicated in the auto zone link.
    You should also have a coolant temp sensor in the back side of the block IIRC.
    I never had an I6 so maybe some other person will chime in.

  24. #24
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    here u can see them both. To the left double temperature switch (4-pol) and the right is the temperature switch for automatic ac.

    In realoem they have switched place with eachother compared in real life.


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  25. #25
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    I think that it depends on the MY. IN the M52 (96 - 98), the dual temp switch / sensor is #6 in the diagram above. I know because I've played with it quite a bit while trying to determine temperature issues in my 1998 528i. I believe that it move to the rear of the block in the M54. I'm not sure about the M52TU which was in 1999, at least.
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