New Car

The diagnostic computer should tell them exactly what's up. Basically the ECU has decided it is not happy with a reading from one or more sensors, or it hasn't been reset since the problem was fixed. If the light was off but came back on, then that would suggest that the ECU was reset, but the original fault has not been fixed.

I know its no fun, but I would insist that they fix it before your warranty runs out, as it could get costly.

It is quite possible that a junior mechanic simply checked the component that the ECU said was faulty, found it to be ok, and gave you it back. In fact it could be something as simple as a wiring connector that is mucky and not carrying the signal properly.

What light is it that is on? In your handbook their should be a list of all the lights with their symbols, and what subsystem they represent.

I wouldn't ignore it for two reasons. Firstly, it will do your head in after a while, as you'll find yourself constantly wondering if it is all ok. Secondly because if another fault develops in the same subsystem, your ECU will have no way to warn you because the light is already on.

 

I'd say the car was a dog and probably traded or sold because the previous owner was fed up with all the faults. If it were me I would be car shopping and cashing in my no quibble walk away guarantee. Doesn't matter how nice the garage is, there's customer service and there's flogging a dead horse, or car in this case.:dh:
FWIW Renaults are notorious for electrical faults.:(

 

the diagnostic machine showed up 2 faults then they fixed that and everything was fine then this sort of squiggly light came back on it must be a warning light, but the car is running just fine, my son in law used to work for renault and he says the megane is a good car, normally when you buy a second hand car you get little things wrong its always the case, in fact a friend of mine bought a brand new audi A4 and had so much wrong with it, i guess its luck of the draw when you buy any car.
this car is fine its running great just a couple of little faults we just need to find out whats causing this light to come back on as its not affecting the running of the car

 

On most cars, you have warnings lights for brakes, seatbelts/airbags, and one or more for the engine. They are not all just engine related. This is why I'd make them fix it. I'm sure you wouldn't be happy to drive it if it turns out it is warning you of a fault in the brakes, or the seatbelts and airbags. The trouble is, under normal driving conditions the fault might not show any symptoms at all. I don't want to scare you but it could be when the manure hits the fan that you find out what the car was trying to tell you. Even if it is engine specific, it may be burning more fuel or sooting up your catalytic converter. It could even be warning you that the emissions are outside of normal parameters, which would be an MOT failure.

I once bought a 3 year old car and the airbag lights kept coming on. I let the garage try to fix it twice before giving up and making them take the car back. They kept telling me that everything was fine but the way I looked at it, in the unlikely but possible event of a crash, I didn't want to find out at as I'm heading towards the dashboard at 70mph that the airbag doesn't work.

I know it is really sad and frustrating when you just want to enjoy your new motor, but cars don't come cheap, and you really need to make sure you get something you can happy and confident with.

 

clueless its just had an mot, had a new exhaust fitted and new brakes, the day we bought it, then we picked it up 2 days later and everything was fine, these lights just started coming on 2 days after we got it, it was the air con yet its had 2 parts and the guy drove it around till we went today and that light showed up, it is going back in and they are giving us another car to drive, lets hope they can find out.it sounds ok when i drive it.

 

I'm sure it will all work out ok, as long as you keep on at them.

 

thanks clueless, they were going to keep car it was hubby that said he would take it, so they said well give it a few days and call them and bring the car back cos they want it sorted, they are going to put it back on machine and have another look, its very frustrating when daft little things happen im sure its nothing major as its running like a dream

 

Had a quick look at an on-line Handbook .On Page 1.37 it says that the wavey line indcates an Electrical or Electronic fault (nice and specific!) and advises you to contact your Renault Dealer as soon as possible. Personally, I'd take it back and tell them to keep it until they know exactly what the fault is and have fixed it.

Looking at some of the Renault Forums, (eg here) it seems that water leaking into the Relay box is a common problem with the Megane and causes / can cause the symptoms you're describing.

 

thanks doogle looked in the handbook about fault, the car is going back to the garage, why they cant find the fault after they put 2 parts in, obviously they must of thought they fixed the problem, it states its an eletrical fault but doesnt state what it is or were it is on the car, just to take it to a renault dealer as they are qualified to fix the problem on these cars and didnt buy the car from them.

 

hubby just took car to a local garage and they put it on their diagnostic machine and hes found the 2 faults, so hes called the garage and the guy told him to bring car straight up to fix it and hes going to get the £25 he paid to find these problems.
fuel pressure regulator, fuel circuit fault
EGR valve position sensor circuit unidentified electrical error
so now we know the problems and it should be fixed soon

 

Good job they found the faults, given what they are. If the fuel pressure is not well regulated, then the engine won't run as efficiently as it could. The EGR (Exhaust Gas Recirculation) valve is responsible for sending unburnt/partially burnt fuel in the exhaust gases back into the intake so that it can be burnt again. The engine management computer needs to be able to adjust the EGR valve position precisely to channel exactly the right amount of exhaust gases back through. Too much and the car will splutter and conk out. To little and although performance won't be affected in any way in the short term, the catalytic converter will quickly become clogged and you'd be looking at an expensive repair. The EGR valve is a common culprit for MOT failures when they do the emissions part of the test.

At least it sounds like you're onto a winner now that they know what the problems are. Should be sorted pretty soon I reckon, then you can enjoy your new motor, which might actually be even more lively once the fueling problems are fixed.

 

thanks for info clueless, im just so suprised these faults were not seen when it went through its mot after we bought it, its back in garage, loan us a car but dont know when it will be fixed as the garage closes over the weekend, at least we have a car to potter about in, lets hope i get it back pretty soon, joining the AA also. keep you informed when i get it back
just printed this out what you said and hubby said thanks for info and also the other garage said its not likely that this would show up on mot that part of test

 

Who put the MOT on? Was it the garage that sold you it?

Faults with the fuel system are not picked up in an MOT unless there is either a leak, or excess emissions. A leak is very unlikely on a car of that age, and the emissions may be fine for now, even with those faults, but would get progressively worse over time.

 

yes clueless garage that sold us car mot it from garage next door to them as most of his cars that he sells are not mot, just edit last bit as above regarding mot

 

hi peri, yes cars are very complex iff things go wrong but we are pleased we know the problem now and its getting fixed before any major things go wrong, lets hope when i get it back the weather turns nice then i can have the roof down haha and start to enjoy it as its a lovely car