Coolant temp sensor

[Jonnybravo]

I still have a few issues with the S2 overfuelling and the water temp being low on the dash, my suspicion is now that the coolant temp sensor is faulty and I'm going to change it. I popped into my local Audi dealership and they wanted over £100 for the sensor so I'm trying to find one through euro car parts or similar but nobody lists a 4 wire sensor for the engine except Audi ?

Is the sensor located on the underside of the inlet manifold ? I have found a brown sensor with a rectangular 4 pin connector which I assume is the CTS ?

Does anyone knows the correct part number for the item I need or if infact the sensor is a 2,3 or 4 wire sensor ?

The car is Dests old avant, so 1995 20v model

Thanks in advance

[s2driveruk]

MFTS (multi-function temperature Sensos is on the water rail just below the IM, so sounds like you have found the right one. Early ones had 4 pins, later have 3.

I would suggest that Vagparts will be able to come in well under £100, sure mine was about £40 when i replaced it last year.

Depending on exact symptoms, I guess you could also look at the age of the thermostat and the lambda too as they will have an effect on temp and fueling....

Cheers
David

[Jonnybravo]

Thermostat is here ready to be changed, I just haven't had the time yet though. The sensor that arrived from Euro Car Parts was a 3 wire sensor which was done on a number plate check, its definately a 4 pin connector, just maybe only 3 wires going to it ? maybe I should check that.

Any links to vagparts ?

[merlin's S4]

Thermostat is here ready to be changed, I just haven't had the time yet though. The sensor that arrived from Euro Car Parts was a 3 wire sensor which was done on a number plate check, its definately a 4 pin connector, just maybe only 3 wires going to it ? maybe I should check that.

Any links to vagparts ?

The 3 pin/ 4 pin thing is fine. They're a straight swap. The extra pin is just a 12v feed which you don't need on the 3 pin version!

[Paulgo]

Just replaced mine and it was about £60 delivered from Vagparts Well worth doing as I hadnt realised the dodgy MTFS was also slightly retarding my boost!

cheers

Paul

[Jamo]

Why do you say the coolant temp is low?

Judge it from the attached pic

If the sensor was knackered you wouldn't get any boost as it triggers an ecu alarm

[Jamo]

Forgot to add if your overfueling and you think it's the sensor related to water temp you've got the wrong one. the MFTS is for the dash alone, the ecu reads it's temp from the sensor in the cylinder head near the turbo erm G62 from memory

[redz]

I had the same problem the temp only climb up when at a stand still and was only pulling 0.6 bar.. Changed the thermostat and now runs 1 bar also runs smoother. Will be looking at changing the lamba probe wjen the zorst gets done..

[Nj]

is the coolant temp sensor not the lonely chap on the back of the block or is that just the 3b? Have you pulled codes?

[johne]

The coolant temp sensor for the ECU is indeed the lonely looking chap on the back of the block and this is the sensor the ECU uses to determine fueling relating to engine temperature.

The MFTS has nothing to do with fueling on the ECU. The only signal the MFTS sends to the ECU is an overtemperature one, which does indeed cause the ECU to reduce boost until it thinks the engine has cooled sufficiently.

[Jamo]

Yeah there's two, the one in head is the one the ECU uses, the one in the rail is the one in the gauge uses ( MFTS )

If the MFTS fails it can cause a false alarm to the ECU which reduces boost but wouldn't affect fuelling afaik that would be the G62 in the head in that case.

S2central.net has a great write up on it.

[Nj]

think the coolant temp sensor was £38 from dealer by the way

[Paulgo]

think the coolant temp sensor was £38 from dealer by the way

Yep - Just found my vagparts receipt at it was £47 all in (inc vat) not £60 doh!

The switch didnt effect the gauage tho and mine has always read a little low cruising, about 3 notches off the 90 in the pic above, but I dont think thats unusual.