Disconnect battery... ECU reset? - Renault Forums :: Independent Renault forum

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post #1 of 7 (permalink) Old 8th January 2006 Thread Starter
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Exclamation Disconnect battery... ECU reset?


I have been looking at buying a megane 1.9 TDi RT Sport, and on the test drive I noticed that an engine light comes on when your foot is not pressing the gas. The light is red with a horizontal zig-zag pattern on it. The light turns off when you apply the pedal. The engine also seems to idling quite high at 1500rpm but I have never purchased a diesel so I don't know if this is normal!
The seller assures me these two things are related-- because "the battery has been disconnected for a while, and the ECU needs to be reset ("zapped" in his words) by a Renault garage."
I personally find it hard to believe that disconnecting the battery would cause this kind of problem, people have to disconnect the battery all the time to do bits and bobs to their cars! But having said that maybe an extended period of disconnection could cause its capacitors to discharge and for the ECU to reset to default.

Does anyone else have an experience of this kind of problem after disconnecting the battery- or is my man lying to me?

Any idea of the kind of cost I would (inevitably) get charged by the renault garage?

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post #2 of 7 (permalink) Old 8th January 2006
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I would walk away from the vehicle straight away. Your asking for trouble!

EX Renault Dealer Technician & MOT Tester, Not a Monkey!
For as long as but one hundred of us remain alive, we will never on any condition submit to the domination of the English.....It is not for glory, nor riches, nor honours that we fight, but for freedom alone, which no good man gives up except with his life. Arbroath 1320
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post #3 of 7 (permalink) Old 8th January 2006
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As WebCode says, if they guy is not intending to get this work done prior to you buying, you might as well look for a different car. You can afford to be choosy unless you are looking for something really exotic, and any problems like this should really be avoided...
post #4 of 7 (permalink) Old 8th January 2006 Thread Starter
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Cheers for that, I think you're probably right, but apart from that and a new CV boot my mechanic (of over 10years) said the car was fine. And it drove fine for just over an hour.

You say you're a technician- do u know what the problem might be and is his story legitimate? Can't call my mechanic- its sunday! I guess if it needs a new ECU it'l proabably cost 500 odd. But might just be idle control value, MAP sensor or throttle sensor. What do you think.
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post #5 of 7 (permalink) Old 8th January 2006
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I think you have had good advice from two knowledgeable members above, walk away!

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battery , disconnect , ecu , reset

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