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coolant problem

Discussion in 'A4/S4 forum(B5 Chassis)' started by audi-a6, Apr 9, 2012.

  1. audi-a6
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    audi-a6 Member

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    a while ago i had a problem where my temp gauge didnt work, so i changed the sensor and made no difference, turns out i had to change the thermostat, so changed it along with the cam belt ect......... and then temp ran as normal (well, never reached 90 but was defenatley working), a few weeks on and i noticed my temp gauge not rising again, done a scan and got code 16500 temp sensor, cleared the code and came back, then again and again........done a scan today and the same code came up after 3-4 reads but now comes up no codes....... so is it the sensor??? i don't really see how a thermostat can go again that quick, can it?????
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  2. ScottD3
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    ScottD3 I want your faulty electronics

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    Genuine Thermostat?
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  3. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep

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    as above some most aftermarket last a few months at most and **** up
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  4. audi-a6
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    audi-a6 Member

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    hmmm, i dont know if it was or not, i got code 16502 now??????
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  5. Mike B
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    Mike B Member

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    Fitted a Europarts stat to my sons S3 last yesr and it failed within a few weeks.Now has a genuine one and thats the lesson
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  6. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep

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    that code points to a CTS
    16502/P0118/000280 - Engine Coolant Temperature Sensor (G62): Signal too High [h=4]Possible Symptoms[/h]
    • Difficulties with starting a cold engine.
    • Starting the engine when engine is warmish or warm, idle rpm immediately is 1200 - 3000 rpm.
    • RPM at idle is irregular.
    • With all engine temperatures idle rpm will often vary between 900 - 1000 rpm.
    • With engine warm (90 °C) the engine temperature suddenly drops (70 °C) and slowly comes back to 90 °C.
    • Bad acceleration during warm-up.
    • Diesel Engines: Glow plug indicator may be on for a longer than normal time or at ambient temperatures where it shouldn't come on at all.
    [h=4]Possible Causes[/h]
    • The electrical signal coming from G62 is too low
    • Wiring and/or connections faulty (short circuit?)
    • Engine Coolant Temperature Sensor (G62) faulty
    [h=4]Possible Solutions[/h]
    • Check wiring and connections
    • Check / Replace Engine Coolant Temperature Sensor (G62)
    [h=4]Special Notes[/h]
    • In many cars between MY 1995-2002 the G2/G62 had a bad reputation for failing often. The original G2/G62 sensor is black and
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  7. audi-a6
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    audi-a6 Member

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    hmmmmm, if i drive from cold for say 2 mile, then stop and go to start it has to turn over alot more times than normal..... also when cold there is a slight delay when putting foot down...... but above it says the sensor is black? mine is a blue one with 4 pin and is square (assuming it is the one at the back left of the engine?)
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  8. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep

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    id get a new CTS from audi
    not to much £££ and you should get the gauge back
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  9. audi-a6
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    audi-a6 Member

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    yeah will try and get one 2moz, if its not that, would you say its up to the garage that changed the thermostat in the first place to rectifie it?
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  10. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep

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    all depends on the garage
    if they fob you off
    i dont know what part was fitted did it have a warrenty ?
    i know all audi parts have a 2 year so if they fail garage claim back on the part
    but they may make you pay
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  11. audi-a6
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    audi-a6 Member

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    suppose if it comes to it i will have to just speak to the garage
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  12. audi-a6
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    audi-a6 Member

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    just been looking and i think iv confused my self as both codes 16500 and 16502 indicate g62 cts, which is the one at the back right of the engine, but its my gauge that is not working which points to the one on the back left? so which one should i change?
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  13. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Its the same sensor.

    should be green and have four pins.

    First off, did you buy a genuine Audi sensor? If not, then go do that to rule it out.
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  14. audi-a6
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    audi-a6 Member

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    there not the same, one is blue 4 pin the other is black 2 pin? but i just bought both, from audi, going to fit them in a bit fingers crossed it sorts the problem
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  15. audi-a6
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    audi-a6 Member

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    o, the one at the front of the engine is green and is 'D' shape
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  16. jcb
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    jcb Active Member

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    I have just changed the CTS on my A6.
    first off you can get Genuine without being raped by the dealer. I got a genuine Febi Bilstien CTS for £18 posted.

    My guage was reading zero but I didnt have any of the other symptoms that a CTS failure can show.
    the only thing that made me check it was the HC reading on a exhaust gas emmisions test was reading high.

    changed the CTS and its fine.
    I didnt have any codes either
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  17. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    I think your getting somewhat confused here.

    The 2.7T has three temp sensors, two of which you'd never even know if they were working or not under most conditions.

    There is a 4 pin (green, blue or even black if its old) sensor at the rear of the drivers side cylinder head. This sensor provides temperature readings for the ECU, AND the dashboard guage. This is the one you need to replace, and this is the one that i'd suggest you ONLY use a genuine Audi sensor bought from the dealership. Fitting aftermarket parts here can cause lots of "Weird ****" to happen.

    Then there is a 2 pin sensor at the rear of the passenger cylinder head, this is ONLY used to control the afterrun pump.

    Lastly there is a 4 pin sensor on the lower radiator hose, this is a switch to control the electric radiator fans.


    The sensors are NOT interchangeable, you must use the correct part in the correct place.

    So before you go any further, what exact parts have you purchased? and what exact parts have you replaced so far...
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  18. audi-a6
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    audi-a6 Member

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    a big sigh of relief!!!! problem fixed ;-)
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  19. audi-a6
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    audi-a6 Member

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    i first replace the 4 pin blue drivers side, made no difference, then changed the 2 pin black passenger side and problem fixed, i know what you mean about the different sensors and the jobs they do, so its very wierd how changing the fan after run one has fixed the problem......
    #19

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