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Temperature drops when driving on main roads???

Discussion in 'Audi S4/A4/A4 Cab (B7 Chassis)' started by Def-87, Jun 24, 2013.

  1. Def-87
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    Def-87 B7 2.0 TFSI Quattro

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    [Jun 24, 2013]
    ​I've had my a4 b7 for a year now and recently I have noticed that when I am driving around town it will sit at 90 degrees.

    When I am on the main roads doing 70-80mph the temperature gauge drops to 70-75 degrees??
    Is this normal? Do I need to replace sensors? Or the temperature sensor?

    Any help would be much appreciated
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  3. Amason007
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    Amason007 Member

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    [Jun 24, 2013]
    I would say that is not normal. Mine stays @ 90 Degrees wether I'm driving on motorway or around town. Not sure what would need replacing. Most probably the thermostat is faulty but I'm sure someone with more knowledge will tell us!
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  4. Pat.
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    Pat. Member

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    [Jun 24, 2013]
    +1 on the thermostat
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  5. Paul B7
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    Paul B7 Active Member

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    [Jun 24, 2013]
    Mines the same, constant 90 all year irrespective of where I am driving or the speed.
    #4
  6. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep VCDS Map User

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    [Jun 24, 2013]
    new stat needed
    #5
  7. Def-87
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    Def-87 B7 2.0 TFSI Quattro

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    [Jun 24, 2013]
    DIY job or easier to book it into the garage????
    #6
  8. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep VCDS Map User

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    [Jun 24, 2013]
    easy swap
    buy oem tho the aftermarket stuff tents to fail
    #7
  9. Def-87
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    Def-87 B7 2.0 TFSI Quattro

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    [Jun 24, 2013]
    Do you know of any DIY threads to follow

    The thermostat you reckon has failed??
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  10. PetrolDave
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    PetrolDave Well-Known Member

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    [Jun 24, 2013]
    Sounds like the thermostat is stuck open.
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  11. Treeoflife
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    Treeoflife New Member

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    [Jun 24, 2013]
    Hi, I've got the EXACT same issue. Doing 40-50mph on the dual carriage way will slowly bring the temp gauge down to 70-75.

    Audi looked into this while my car was in for brakes. I asked them to replace the thermostat as I self diagnosed it. (Makes sense it would be stuck open). Audi said it was fine and didn't replace it. Apparently temp sender was was too.

    I've decided the thermostat is fine. With the engine cold, pop the bonnet and start the car. If the thermostat is stuck open, you'll be able to see the liquid circulating (ie look at the reservoir tank. If the thermostat was stuck open, you'll be able to see it dump the fluid in the tank) Audi want the car for a couple of days to investigate. Unfortunately I don't have time off work until then end of July.
    #10
  12. Def-87
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    Def-87 B7 2.0 TFSI Quattro

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    [Jun 24, 2013]
    Is this the plug where the coolant sensor is situated???


    [​IMG]
    #11
  13. Def-87
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    Def-87 B7 2.0 TFSI Quattro

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    [Jun 24, 2013]
    Just run car on VCDS and this fault came up

    1 Fault Found:
    008577 - Performance Malfunction in Cooling System
    P2181 - 008 - - Intermittent
    Freeze Frame:
    Fault Status: 00101000
    Fault Priority: 0
    Fault Frequency: 1
    Mileage: 162527 km
    Time Indication: 0

    Freeze Frame:
    RPM: 1875 /min
    Load: 31.0 %
    Speed: 54.0 km/h
    Temperature: 74.0°C
    Temperature: 22.0°C
    Absolute Pres.: 1000.0 mbar
    Voltage: 13.970 V

    I guess this verifies the thermostat??
    #12
  14. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep VCDS Map User

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    [Jun 24, 2013]
    id say stat as if it was CTS it would be acting diffrent

    18613/P2181/008577 - Performance Malfunction in Cooling System [h=4]Possible Solutions[/h]
    • Check Engine Coolant Temperature Sender (G62)
    • Check Coolant Thermostat
    • Check Engine Cooling System
      • Put the key on, fan speed on 1, and push the a/c switch. Are both fans kicking on? If not, you found the problem.
      • Put the key on and fan speed on 1 with temperature set to hot. Does heat come out readily from the vents?
        • No. Probably the water pump is gone.
        • Yes. Probably the thermostat is gone.
    [h=4]Special Notes[/h]
    • Check the stored Freeze Frame data with this fault code. Freeze Frame information will be found in the fault code description (if the module supports it) or in Generic OBD-II if the vehicle complies with those regulations.
      • Freeze Frame data stored at -40*C is generally an indication of a faulty ECT or wiring.
      • Freeze Frame data stored at +140*C is generally an indication of a faulty ECT or wiring.
      • Freeze Frame data stored with in the 68*C ~ 80*C range is an indication that the vehicle was close to, but not within, the cooling systems normal operation range. The Thermostat itself or Cooling system components may
    #13
  15. Big Al
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    Big Al A4 sold, a Lupo for now!

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    [Jun 24, 2013]
    My (faulty) A4 B7 TFSI Quattro does the exact same -but has a hesitation problem too - see my thread. Does your car drive okay otherwise?

    http://www.audi-sport.net/vb/audi-s...-2-0-tfsi-engine-stalling-intermittently.html


    My car is currently at Coventry Audi being investigated (for the 3rd time!). The technician who accompanied me on a road test noticed the temp fluctuation the same as yours. So far they haven't found out what's going wrong....
    Last edited: Jun 24, 2013
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  16. Def-87
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    Def-87 B7 2.0 TFSI Quattro

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    [Jun 24, 2013]
    Checked a/c and the fan is kicking in properly.

    Hot air comes out of vents so it cant be water pump.

    My car drives perfectly and very smoothly, my clutch sensor was replaced when i retrofitted cruise control (common fault)!!

    I would be interested to know what your outcome is from audi on the temp fluctation as if it is thermostat then i will get it booked in.
    #15
  17. Big Al
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    Big Al A4 sold, a Lupo for now!

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    [Jun 24, 2013]
    My AC and heater are working fine too. Glad to hear your car drives perfectly, my clutch sensor was changed on the last visit. Sure I'll keep you updated, have subscribed to this thread.
    #16
  18. thehogester
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    thehogester Member

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    [Aug 26, 2013]
    I'm having this issue exactly. Temp rises and falls dependent on my driving. Can the thermostat itself be replaced, or is it the entire unit that has to be changed?

    Can anyone tell me the part number, or even link to the part?
    #17
  19. Molnboman
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    Molnboman Well-Known Member

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    [Aug 26, 2013]
    If I remember it's a sealed unit so you can't change parts inside the unit. This is the petrol part number. EuropaParts.com: Thermostat (A4 B7, 2.0T) - 06D121111G It can be bought from any VAG dealer in the UK. Not recommended to use other than OEM.

    Cheers
    A
    #18
  20. OxfordRich
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    OxfordRich Collecting Rings

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    [Aug 26, 2013]
    Temp rises and falls with driving, and it's a repeatable experiment? Thermostat, end of story.

    Mine went (Audi A4, 2.0T FSI) and you need the whole unit, you can't just change the actual brass 'stat on it's own. It's a 3 hour ***** of a job, I've done it. There's a DIY guide.
    #19
  21. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep VCDS Map User

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    [Aug 26, 2013]
    most people remove the alt to get to the stat
    i dont and its not realy that hard fiddly yes 2 hour max with right toos and a few brews
    #20
  22. Big Al
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    Big Al A4 sold, a Lupo for now!

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    [Aug 26, 2013]
    Thanks for the reminder regards an update. The dealer changed the coolant temperature sensor G62 which is back left of the engine above the CAT (not the best design in a hot area!). This made the gauge itself work better (sometimes before it stopped working). The thermostat unit described above was then changed which did cure the temperature fluctuation issue.

    But my car still hesitated, so next I changed the MAF G70 (which was filthy from previous owner not changing air filter often enough). This made the car smoother to drive - hesitation still existed.

    So next I plan to change the Engine Speed (rpm) Sensor G28 - also known as the Impulse Sensor or Crank Sensor.
    #21
  23. OxfordRich
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    OxfordRich Collecting Rings

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    [Aug 26, 2013]
    Sorry to hear the car is hesitating.. yes, I once went to a main dealer and their diagnostics style was the "lucky guess" approach then too :)

    Bez - if you can do it in 2 hours without removing the alternator then you're some sort of god and got lucky with removing the pipes from the thermostat housing.. this part took me 40 minutes. I'm sure you're very handy but would stand by my 3 hours :)

    p.s. Bez did you used to own a Cupra or perhaps I'm confusing you with someone else off SCN.
    #22

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