Renault megane starting problem

31 Aug 2006
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United Kingdom
Hi all.

I have a V reg, 1.4 Renault Megane Elise.

The problem that I am having is that sometimes it will not start. It always seems to start in the morning when the engine is cold. But if I turn off the engine for a few minutes(while getting fuel for instance) it sometimes then fails to start. It usually starts after a while though.

I have taken it to the mechanic but they could find nothing wrong despite keeping it for over a week. I don't think that they could even get it to happen.

Does anyone have any ideas of what could be wrong?

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Do you know if the lambda switch checked? this what happened with our clio, it got worse as time went on till it would'nt start at all. until replaced.
Check the wiring on the Lambda probe - engine loom for corrosion, its common on them.
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More likely to be the coolant temp sensor than the lambda probe. Lambda should only kick in when the engine is running
Thanks for the replies.

when this problem occurs does the engine turn over and not fire or is it totally dead

Yes the engine does turn over.

More likely to be the coolant temp sensor

Is this similar to the top dead center sensor?

I found this information on another forum.

"Symptoms of a Faulty Top Dead Centre Sensor.

The Top Dead Centre (TDC) sensor tells the Engine Control Unit (ECU) where top dead centre is on the engine.


1) Engine cranks but won’t start
2) Engine begins to idle roughly
3) Engine won't kick over when it is cranked
4) Engine fails to start after a hot run, i.e. won’t start until cooler


The sensor is located on the top of the bell housing. It is a small black cylinder with a little metal point on the end and has a banana shaped metal bracket with the sensor attached.

Remove sensor and wipe with some contact cleaner to see if this rectifies the fault. If not a replacement is required (approximately £17)."

My car seems to have symptoms 1 and 4.

Do you think that this could be the cause?

Yes it could be, but it could also be the coolant sensor as^ Neo^ suggests or even some other sensor, the only way you are going to find out is by substitution or have a fault readout done.

Could also be the TDC sensor (the french do have to name things different dont they!) but the coolant temp sensor would be the cheapest to change, and would explain why its a pig to start when hot.
i would bet my life its your top dead sensor, its located at the top of the bellhousing (where the gearbox bolts to the side if the engine) think its on the right hand side as you look at it, its held in with x2 10mm bolts, a semicircle piece of metal with a thing about 30mm coming down off it (bout the same thickness as a pen) check the multiplug to this is ok, but remove the sensor, giv a clean with fine sandpaper then replace. should help, a new sensor is about 15quid frm GFS

I asked my mechanic what it was that he changed when I took the car in. He said it was the temperature sensor. Would this be the same thing as the coolant temperature sensor, or something different?

Thanks alot.
Yep, thats the one.

Tells the computer on the car what temp the engine is so it knows whether to supply more (cold) or less (hot) fuel. Thats why when you start it up from cold it will always idle (rev) higher than when the engine is warm.
Ok cheers. I guess I'll start by taking a look at the Top dead center sensor then.
my x reg 1.6 megane is having a starting problem. It turns over but just ownt start, if i keep trying it eventually starts. Battery is fine and when it starts it runs perfectly.

What could it be?
is this the TDC sensor, the black wire going into the bent bar with holes in it? I cant remove it as the bolts are too tight.
The car does NOT run rough when it gets going and idles perfectly. So could this issue still be the TDC sensor?
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