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Robert, UK Qualified Car Technician
Category: Car
Satisfied Customers: 4716
Experience:  Fully qualified / self employed garage technician in the UK
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I have a renault megane,I think there is a problem with the

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I have a renault megane,I think there is a problem with the immobiliser. The engine turns over but is difficult to start sometimes. The battery is fine.


Hopefully i can help..

What year and engine does this car have?

Have you had issues with the key or depending on year the - keycard before?

Any warnings up on the dash prior or during the fualt?

When its started does it start ok when warm throughout the rest of the day etc?

Customer: replied 3 years ago.

a. The year is 1999 and engine size is 1.6 petrol

b. I have tried both keys but still have the same problem.

c. No warnings up on the dash.

d. Once the engine starts it works fine.

This problem has been happening for some months now. There is no warning as to when it will happen. The vehicles starts fine for several days then it happens again. The car was fully serviced recently and the garage could find nothing wrong.

Hi..there thanks for your responce.. doesnt sound like immobiliser releated especially so if the engine seems to start and stop ok when warmed up etc..normally immobiliser issues tend to be all the time during starting intermittent or stops the car starting alltogether - one thing to may have checked out if not already inspected that comes to mind and isnt an unknown problem on Renaults - petrols mostly is the CKP sensor or flywheel sensor as it is also known by - if the signal from that and the flywheel gets interupted then you can loose spark or the engine doesn't fire up or cuts out intermittently usually when coming to halt at junction for example depending on how the sensor going faulty - and "can" sometimes but not always cause the fault warning to come up - so i would maybe start there first - you can remove it "sits above the gearbox bellhousing via*****shaped bracket with the sensor in the centre" and clean up the tip on the sensor as sometimes they get fouled with iron filings and this can cause a poor signal - then refit and see if that solves the issue - if not then you could maybe try a new one anyway - ideally from the Renault Dealer as appossed to an aftermarket type - as the dealer will have an updated sensor/loom - another is the ECT sensor - this normally acts a cold start sensor so that would be another item to check - I would also too check pretty much all earth points within the engine bay and too the engine for corrosion/etc aswell as checking the wiring back from the coils/plug connector and too the engine bay main relays are secure and not loose/or show signs of moisture/water these are a few starting points anyway and see how that goes..I do hope this helps

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Customer: replied 3 years ago.

Thanks Robert, I will try the things you have suggested.

Hi..there - no problem glad to help.. and many thanks for rating most appreciated..if you need to ask anything further then just continue after this post if of luck Robert

Customer: replied 3 years ago.

Hi Robert, sorry to have taken so long to reply to you.... anyway the the advice you gave me was spot on, it was the sensor that was the problem. I bought a new one, fitted it and the car now starts first time. Thank you very, very much for your help and advice.



Hi..there JT..

Yeah thats no problem at all glad to help - Good to read you managed to get it sorted out and fit the sensor yourself.. ;) - If you ever need to ask anything or need advice then just look me up and i'll be at to glad to help as best i can.. Best of luck Robert