Renault Scenic Mark 2 2005 auto transmission advice sought

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Diaron

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Melbourne
The car starts and runs well but eventually the temperature gauge in the instrument panel starts decreasing from about five bars and eventually no temperature read out at all. At this point or shortly after the auto changes become a bit erratic. The temperature gauge can reappear, and gear changes recover until temperature gauge drops out again. Engine coolant at required level and engine cooling fan cuts in about five bars (when showing) and engine shows no sign of overheating. I have been told the engine temp. sensor and the auto box temp. sensor 'talk to each other'. Is one or other faulty? Has anyone else had this puzzling experience?
Diaron
 
Hi Diaron I think the answer will be found by reading the codes. Possibly any code reader will give you some codes information that points to which one is faulty. Or there is a faulty wire or connector that is affecting the reading. Repco/Supercheap etc will read the codes for a small fee. Write them down before they attempt to clear them and see what happens after that.

The ECU certainly monitors both the temperature sensor circuits and reacts to what it sees as a reading that is outside the normal range. If the ECU decides the reading might cause damage it will down grade the operation of the transmission or the engine or both to limit damage.
Jaahn
 
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jaahn said:
Hi Diaron I think the answer will be found by reading the codes. Possibly any code reader will give you some codes information that points to which one is faulty. Or there is a faulty wire or connector that is affecting the reading. Repco/Supercheap etc will read the codes for a small fee. Write them down before they attempt to clear them and see what happens after that.

The ECU certainly monitors both the temperature sensor circuits and reacts to what it sees as a reading that is outside the normal range. If the ECU decides the reading might cause damage it will down grade the operation of the transmission or the engine or both to limit damage.
Jaahn
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Just to add a bit more on what Jaahn said above, look at the live data while you are driving around so that will give you a good clue to what is really happening.

You will need a code reader capable of reading live data and co-driver to look at the data as you drive.
 
I'm not a Renault man, but attached are some pages that may be useful.
 

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I'll be interested to hear more! Faulty temperature sensor comes to mind but the codes should give a hint if not a definitive answer. You'd think if it were overheating the apparent temperature on the gauge would rise past the 5 bars. I'm really responding to say that all three of our Scenics also sit on 5 bars. Never more or less once warmed up. Ours are manuals so I can't comment on the auto issue.

The UK Renault forum has a Scenic area - they probably have 100 times more of them, and I've found it a useful place.
 
I should have said-- those pages are from the official Renault Scenic 2 manual. The third file concerns the temperature. The other two are referenced by it.
 
Many thanks to all who have responded to our post. My nephew, (it's his car) and I have read through all suggestions and have decided to get a new engine temp sensor and use a code reader to check things out. Will keep you posted as to the outcome. Our logic is that if the temp sensor is telling the engine management unit that the engine is getting colder even though it is warming up and to the extent that the visual gauge eventually disappears from sight resulting in the engine management unit staying in "choke" mode resulting in poor engine behaviour. Furthermore, we have been advised that the auto box varies its behaviour depending on whether the engine has warmed up.
 
Also check to see if the transmission solenoids have been replaced. They also cause rough running.
 
they respond well to two or three oil changes in the auto, you can only drop about half the oil at a time ,probably not the main cause of your problems but ,worth doing ,once you get it sorted ,do a search on here there is a fair bit ,on this subject
 
pugwash said:
they respond well to two or three oil changes in the auto, you can only drop about half the oil at a time ,probably not the main cause of your problems but ,worth doing ,once you get it sorted ,do a search on here there is a fair bit ,on this subject
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"A fair bit" is quite a summary! :)

Mr Diaron, best wishes for the diagnosis. I'm not qualified to comment as owner of manual cars but I've followed the years of discussion on these autos (hence buying manual cars myself). My gleanings are that (a) there is an issue with the solenoids and (b) take care with fluid selection.

Best wishes biting the bullet and buying the diagnostic gear. Now for the interpretation eh?

Cheers
 
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