ATF Temperature sensor

[DRDT]

Just had my visit to local OPC for the 911 Health Clinic. Excellent service as always and the bacon rolls were very tasty.

On my way there and unusually given the OAT of 11 degrees, my Temperature Gauge failed when it reached 60 degrees indicated some 6.4 miles after leaving home. It recovered at 7.7 miles and that was it. Now this is fairly normal in the colder weather when the OAT is below 10 degrees but unusual in the summer. OPC Tester showed a 'blocked thermostat' but as I had had this changed and the engine temp sensor as well some time ago we discounted this and the third sugestion was the Tiptronic ATF Fluid temp sensor.

As I understand it this sensor is part of the coolant temp/ATF/Oil package which dictates the Tiptronic mapping when the engine is cold. Its aim is to keep the coolant circuit closed to warm up the engine and ATF quicker and adjusts gear shifs accordingly. I could of course be totally wrong.

At the time of the failure I was doing about 75mph anf the engine still cool. Could this sensor be the underlying cause of the problem I have had ever since owning the car (over 3 years)? I believe the sensor (Part No. 996 605 123 01) is readily accessible from underneath and only a few minutes to change with the part in the order of £70.

Expert advice please - has anybody else had similar problems traced to this sensor?

Many thanks

 

[thirteeneast]

£70 seems al ot for a soloniod valve and a bacon roll.

996 605 123 01 I would offer £20-25.
I think other car makers use that part on cars too try cross reference across other makes.

Good luck.

ORIGINAL: DRDT

Just had my visit to local OPC for the 911 Health Clinic.  Excellent service as always and the bacon rolls were very tasty.

On my way there and unusually given the OAT of 11 degrees, my Temperature Gauge failed when it reached 60 degrees indicated some 6.4 miles after leaving home.  It recovered at 7.7 miles and that was it.  Now this is fairly normal in the colder weather when the OAT is below 10 degrees but unusual in the summer.  OPC Tester showed a 'blocked thermostat' but as I had had this changed and the engine temp sensor as well some time ago we discounted this and the third sugestion was the Tiptronic ATF Fluid temp sensor. 

As I understand it this sensor is part of the coolant temp/ATF/Oil package which dictates the Tiptronic mapping when the engine is cold.  Its aim is to keep the coolant circuit closed to warm up the engine and ATF quicker and adjusts gear shifs accordingly.  I could of course be totally wrong.

At the time of the failure I was doing about 75mph anf the engine still cool.  Could this sensor be the underlying cause of the problem I have had ever since owning the car (over 3 years)?  I believe the sensor (Part No. 996 605 123 01) is readily accessible from underneath and only a few minutes to change with the part in the order of £70.

Expert advice please - has anybody else had similar problems traced to this sensor?

Many thanks

 

[Richard_Hamilton]

I'm confused. The ATF temperature sensor is inside the gearbox, to sense the temperature. The part you are describing is the solenoid valve which controls the vacuum operated coolant flow valve to the tiptronic heat exchanger. It is usually the vacuum feed pipe, from the throttle body, which cracks (or becomes detatched) which causes the vacuum valve not to operate.

When you say the gauge fails, do you mean it goes down to the bottom stop? If so, I would be looking at the water temperature sensor, or the gauge itself.

 

[Jenik1914]

Spooky or what...........I went to the same clinic and had exactly the same fault on the way up at about the same distance from home, in fact If I was writing the original post it would be almost word for word.
I even had the same diagnosis, was your techie's name Lee by any chance?

 

[Richard_Hamilton]

If you are talking about a sudden drop in coolant temperature, which takes a long time to come back up, then this is quite likely to be the vacuum tube I mentioed earlier.

Edit: Sorry! Welcome Nick!

 

[DRDT]

Richard & Jenik 1914 - thank you. I first posted this problem back in Oct '09 on the first occasion of happening. At the time nobody else semed to have experienced the same kind of fault. Indy Paragon and the local OPC looked at it and Paragon changed the thermostat and engine temperature sensor under warranty, although neither were showing as defective. The result was that the failures still occurred but the gauge outages were usually of a shorter duration - 1-3 miles instead of anything up to 10 miles - again muchg depended on the ambient OAT. I have lived with it since and gauge failure, or not, is always a good harbinger of the onset of Winter and Spring as the OAT cooled/warmed below/above 10 degrees respectively. Considered opinion back then was that the problem could lay within the instrument cluster and replacing that was not a cost effective option.

At the 911 Clinic (yes it was Lee and I thought he did a thorough inspection job and patiently cxplained technical issues in layman's language). The gauge failure was really outside the remit of the Clinic but a quick look by Lee with the Tester was much appreciated. His thoughts, having eliminated the thermostat and engine temp sensor, was the sensor you mentioned Richard (sorry I used the wrong term). We checked the hoses around the sensor and all seemed in order so that only leaves the sensor. It was, at least, a rational, different although not categoric, explanation of what might be the cause. I can understand that pushing the car when not at full operating temperature might cause some DME/Tiptronic anomalies.

The failures manifest themnselves without warning when the OAT is about below 10-12 degrees and within 10 miles of starting a journey from cold. As the gauge reaches 60 degrees indicated it drops suddenly to zero and the 1 Hertz warning light flashes together with a warning message on the OBC. After a few more miles the gauge suddenly springs to life up to about 70 degrees, the warning light ceases to flash and the gauge climbs to normal operating temperature over the next few miles.

I live with it as it appears to have no detrimental effect on the car or performance, but I remain curious as to the cause. Not worth spending large sums of money on investigating/part changing without a definite lead as to where the problem lies. However I am pleased that somebody has similar problems - I began to think I was alone with this one.

It would not be the same to have a car without some idiosycrancy anomaly somewhere.