Some bits and bobs I've found out while being the proud-ish owner of a 2002 - 16v, 1.4 Megane Hatch. But may also relate to your car, worth checking out if you have a similar problem because its all free, fairly straight forward and may just make your life a bit easier.
Now this assumes you've already made all the normal checks, HT and air filter etc.
:- Car cranks and cranks then eventually starts, once started runs OK for the rest of the day, then you have to go through the same hassle again the following morning.
:- Found to be the water temperature sensor, half way down the engine on the right hand side as you look from the front. Best to move the air intake out of the way first, remove connector then unscrew and remove sensor. You will have found by this time that you also need a spare finger to stick in the hole to stop all your coolant bleeding away
. Give the sensor a good clean, also make sure connection is good and clean, then replace.
*** Note, tried a garage with this problem first, diagnostics didn't give much of a clue but they seemed to think it was the
sensor (Just below the water temperature sensor, 2 hex headed bolts on a T bar holding it in place) having replaced mine (circa £20) to no avail went on to find it was the water sensor. But worth keeping in mind. ***
- Car starts fine then revs just die, engine stalls/stops. You may just keep it going if you keep the revs up.
:- Found to be the Absolute Air Pressure
. Now this is situated in the top of the air intake at the back of the engine on the left hand side as you look from the front. It's held in place with 2 Phillips screws. Unclip the connector, undo the screws, the sensor just lifts out. Mine looked pretty well sooted up. Carefully (they cost about £45 to replace) give it a thorough clean with a soft dry cloth, a spray with WD40 and wipe dry again before replacing. Also make sure connection is good and clean.
:- Uneven running leading to occasional stall.
:- Air temperature sensor. This is situated on the front of the engine more or less in the middle. You'll need to remove the plastic engine cover first, just lift from the front. Its held in place with metal spring clips. Remove the connector and just prise the sensor out with a screw driver, its only held in place with an O ring and plastic clips. I replaced mine (£8.50) but there's no reason not to give it a good clean and try that out first.
For my part, I'll probably clean all three annually, just to keep things running smoothly.