JMB RetrofitsVolks Autos
Results 1 to 9 of 9
  1. #1
    Nessy's Avatar
    VW + Audi mad

    Status
    Offline
    Join Date
    Oct 2005
    Location
    Bridgend, South Wales
    Posts
    617

    Location of coolant temp sensor on AFN TDi?

    Search as I might I can't find a pic or info as to where exactly the CTS is on my pre-facelift AFN, can anyone please help?
    My temp gauge is giving some very odd and low readings (matching the temperature readings I'm getting on the climate control panel); the thermostat was replaced last month with a Genuine item and the dash vents produce boiling hot air when the heat is turned up.....
    I therefore think the CTS is a prime suspect as the current one (fitted by a previous owner) is 10 yrs old, but haven't a clue where exactly it is to be found!
    Thanks in advance!
    '99 Ming Blue A4 Avant TDi SE 110 + Dragon Performance Tuning Box
    Factory sunroof / Cruise / Aircon + Climate / Royale Blue leather

    '72 1302LS Karmann Beetle Cabrio Silbermetallic

    '63 Karmann Ghia Sunroof Coupe Pacific Blue

  2. # ADS
    ADS
    Join Date
    Always
    Location
    Global
    Posts
    Many
     
  3. #2
    "Stick a V8 in it!"

    Status
    Offline
    Join Date
    Jan 2008
    Location
    Glenrothes, Fife, Scotland
    Posts
    15,391
    Its on the back of the cylinder head in a wee plastic housing.

    If you have VCDS, compare the reading from the engine control unit, with the reading in instruments. If they match, its unlikely to be the CTS.

    2000 A4 1.8T Sport Quattro Avant, Berry Pearl
    2000 A4 1.8T Sport Quattro Saloon, Black-ish
    1997 S4 - PPC £999 Challenge Track Car Build
    TD5 Land Rover Defender build


  4. #3
    Nessy's Avatar
    VW + Audi mad

    Status
    Offline
    Join Date
    Oct 2005
    Location
    Bridgend, South Wales
    Posts
    617
    Quote Originally Posted by aragorn View Post
    Its on the back of the cylinder head in a wee plastic housing.

    If you have VCDS, compare the reading from the engine control unit, with the reading in instruments. If they match, its unlikely to be the CTS.
    Thanks, I only have VCDS Lite?
    Coming home from work tonite on motorway at 70mph with cruise engaged, suddenly looked down and saw dash temp gauge reading approx 70, quickly put CC panel into block 49c and got a reading of 69-70 degrees the rest of my journey until I pulled off the M4....slowed down and gauge went back up to 90??
    CC panel display going no higher than 87.
    Thermostat I hear you say, but all the time at 70 degrees on the CC panel I was getting roasting hot air on demand.
    In the past whenever I've had dodgy thermostats I've had lukewarm air from the vents?
    As the CTS was last changed in 2003 I was hoping that was the cause?
    '99 Ming Blue A4 Avant TDi SE 110 + Dragon Performance Tuning Box
    Factory sunroof / Cruise / Aircon + Climate / Royale Blue leather

    '72 1302LS Karmann Beetle Cabrio Silbermetallic

    '63 Karmann Ghia Sunroof Coupe Pacific Blue

  5. #4
    "Stick a V8 in it!"

    Status
    Offline
    Join Date
    Jan 2008
    Location
    Glenrothes, Fife, Scotland
    Posts
    15,391
    Typical thermostat failure tbh.

    High speed and fairly low load means the engines not emitting much heat and getting lots of cooling. If the stat doesnt close off when it should, the temperature will drop under those circumstances. When you slow down, the reduced airflow thru the rad, typically also combined with more varied driving raising the heat output, means it comes back up to 90.

    70c is plenty hot enough to give you roasting air, so thats a bit of a red herring. If the stat was jammed open and your coolant temp was only 40c or something then i could see the air getting cooler.

    The CTS has two sensors, one for the ECU and one for the cluster. This is why i said check with VCDS, its unlikely that both sensors will fail simulatneously, so by checking the ECU's output and comparing to the clusters output, lets you see wether its the CTS or not.

    In my experience, CTS's fail a LOT less than people seem to think. Most of the time its the thermostat. People either do the CTS first because its "easier", or change both the CTS and stat together when infact its only the stat at fault.

    2000 A4 1.8T Sport Quattro Avant, Berry Pearl
    2000 A4 1.8T Sport Quattro Saloon, Black-ish
    1997 S4 - PPC £999 Challenge Track Car Build
    TD5 Land Rover Defender build


  6. #5
    Nessy's Avatar
    VW + Audi mad

    Status
    Offline
    Join Date
    Oct 2005
    Location
    Bridgend, South Wales
    Posts
    617
    Thanks Aragorn.
    Just to report though that yesterday I changed the CTS and this appears to have sorted things, managed to get a Genuine sensor plus O ring plus clip for less than £20 delivered via Ebay.
    Before the sensor change, the CC display panel (over the last week or so of journeys to work) wouldn't go any higher than 87 or so and the display would be racing up and down between 78 and 87 constantly.
    I'm now getting a constant 90.
    Suppose time will tell if it has cured things, but fingers crossed it has.
    '99 Ming Blue A4 Avant TDi SE 110 + Dragon Performance Tuning Box
    Factory sunroof / Cruise / Aircon + Climate / Royale Blue leather

    '72 1302LS Karmann Beetle Cabrio Silbermetallic

    '63 Karmann Ghia Sunroof Coupe Pacific Blue

  7. #6
    "Stick a V8 in it!"

    Status
    Offline
    Join Date
    Jan 2008
    Location
    Glenrothes, Fife, Scotland
    Posts
    15,391
    90 exactly?

    Doesnt sound right.

    mine runs about 92, and fluctuates a few degrees depending what your doing with the pedal.

    If its not moving from 90 its not working properly.

    2000 A4 1.8T Sport Quattro Avant, Berry Pearl
    2000 A4 1.8T Sport Quattro Saloon, Black-ish
    1997 S4 - PPC £999 Challenge Track Car Build
    TD5 Land Rover Defender build


  8. #7
    Nessy's Avatar
    VW + Audi mad

    Status
    Offline
    Join Date
    Oct 2005
    Location
    Bridgend, South Wales
    Posts
    617
    You're spot on as usual!
    Poor choice of words on my part sorry!
    The new CTS shows a display of mostly 90, but yes it does get to 91-92 depending on what I'm doing with my right foot.
    In my ignorance I just put that down to perhaps a very sensitive new CTS,lol....
    When I first learnt about the CC display panel info several years ago I found/thought? that the temperature my car ran at was 90 bang-on and I have never ever seen it higher than that.
    For that reason I'm wondering if my CTS has been slightly playing up for several years....
    '99 Ming Blue A4 Avant TDi SE 110 + Dragon Performance Tuning Box
    Factory sunroof / Cruise / Aircon + Climate / Royale Blue leather

    '72 1302LS Karmann Beetle Cabrio Silbermetallic

    '63 Karmann Ghia Sunroof Coupe Pacific Blue

  9. #8
    "Stick a V8 in it!"

    Status
    Offline
    Join Date
    Jan 2008
    Location
    Glenrothes, Fife, Scotland
    Posts
    15,391
    The usual error people make is using channel 51 rather than 49. 51 displays 90 constantly once the engines been running a while, whereas 49 shows the actual temperature.

    2000 A4 1.8T Sport Quattro Avant, Berry Pearl
    2000 A4 1.8T Sport Quattro Saloon, Black-ish
    1997 S4 - PPC £999 Challenge Track Car Build
    TD5 Land Rover Defender build


  10. #9
    Nessy's Avatar
    VW + Audi mad

    Status
    Offline
    Join Date
    Oct 2005
    Location
    Bridgend, South Wales
    Posts
    617
    Quote Originally Posted by aragorn View Post
    The usual error people make is using channel 51 rather than 49. 51 displays 90 constantly once the engines been running a while, whereas 49 shows the actual temperature.
    Yes, I've been guilty of that.......
    The new sensor has definitely done the trick though, no more erratic gauge readings!
    '99 Ming Blue A4 Avant TDi SE 110 + Dragon Performance Tuning Box
    Factory sunroof / Cruise / Aircon + Climate / Royale Blue leather

    '72 1302LS Karmann Beetle Cabrio Silbermetallic

    '63 Karmann Ghia Sunroof Coupe Pacific Blue

 

 

Similar Threads

  1. Coolant temp sensor location on 2.0 tdi BLB engine code
    By polo10v in forum Audi S4/A4/A4 Cab (B7 Chassis)
    Replies: 4
    Last Post: 5th March 2013, 20:43
  2. Engine Coolant temp sensor circuit 1 high a3 tdi 2.0?PO118
    By aterro in forum A3/S3/Sportback (8P Chassis)
    Replies: 10
    Last Post: 27th September 2012, 23:50
  3. coolant temp sensor location? (APS) 2.4 v6
    By melteddrummerr in forum A4/S4 forum(B5 Chassis)
    Replies: 2
    Last Post: 13th August 2011, 20:57
  4. Coolant Temp Sensor 2.0 TDi BKD
    By Gti Jazz Blue in forum A3/S3/Sportback (8P Chassis)
    Replies: 4
    Last Post: 16th May 2008, 09:22
  5. Coolant Temp sensor - TDi
    By sprout99 in forum A3/S3 Forum (8L Chassis)
    Replies: 19
    Last Post: 13th September 2007, 12:19

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Single Sign On provided by vBSSO

Garage Plus, Vendor Tools vBulletin Plugins by Drive Thru Online, Inc.

Content Relevant URLs by vBSEO