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Common Issues - Read this first

Posted: Mon Nov 17, 2008 8:38 am
by markren2004
edit: ive started adding some dephaser info.
edit : Added link to the workshop manuals and tech notes index

Looking at the current list of topics today isn't it about time there was a "sticky" about these common issues;
The recent list is full of all the common issues that already been discussed many many times before;
Failing Pencil Coils
Petrol 1.4 / 1.6 / 2.0 ??
These are individual coils that provide the charge to the sparkplug. They are fitted to the top of each sparkplug and kept in place by a 10mm bolt.
A failed coil will mean the engine is firing on just 3 cyclinders and cause it to nearly stall and shake. It also may display the toxic fumes/engine mgmt light on the dash.

How to Test
see viewtopic.php?f=2&t=6200

How to Change
The coils work in pairs (the outside 2 and the inside 2)...and therefore i recommend at least a pair of coils is changed.This is probably one of the easiest jobs that an owner can do themselves.
To change a coil the engine must be cold, first unclip the connector by squeezing one end (like a peg) and pull towards you to release.using a 10mm socket unscrew the retaining bolt and pull the coil upwards to release from the sparkplug.
When refitting renualt recommend some special insulating grease (£40 for a small tube), so needless to say most people put new ones on without. when you refit the electrical connector you should hear a nice click.
repeat for the other in the pair or all others.job done.
tip: if you replace all 4 then throw away the bad pair and keep the good pair as spares.

Toxic Fume / Engine Mgmt Light
The dash light indicates an issue with the engine management...and is usually caused by one or more failed sensors or coils (for petrol) or glow plugs (for diesels)
1.6 vvt
nothing noticeably different with car only the light is sensor.
located right next to coil 4 (passenger side)..need to remove coil 4 for better access. easy to change. sometimes this just needs a clean. see viewtopic.php?f=2&t=7573&p=50936#p50936

1.6 / 1.4
car has trouble starting, stalling sometimes loss of power ...crank (TDC) sensor.
a bit more difficuly to change, located bottom of engine on top of the bell sensors from main dealer have a blue connector and requires some additonial wiring/connector (separate part) to connect to exisiting harness. black ones are the orignals which tend to fail.

generally once a fault has been rectified the light will go out after a number of journeys...sometimes the light needs to be erased by a computer or a special handheld tool. if using a tool, usually need to have the ignition on (but car not started) for the tool to erase codes - to turn on ignition put card in slot and press start button for 5 secs without pressing any pedals.

1.6 VVT Petrol Dephaser (mainly 2002 to 2005)
The dephaser is part of the ignition system that applies the "Variable Valve" technology. It alters the timing of the valves opening / closing to help efficiency.

On cold starts the engine will give an unmistakable grinding/rattle for a second..and probably stall straight away without actually starting. It may then start ok second time (without any noises) and run fine, as the problem gets worse you may need to give it plenty of revs to get it going.
not related to mileage...many examples of low mileage cars with the issue.
If buying a 2002 - 2006 car, this is one thing to check if the car has had a replacement...if not then factor into the price.

People who have opened up failed dephasers have found wear on the oil drain plug that is supposed to open/close...stopping it from closing completely and thus draining of oil. The noise is the drain plug trying to engage (at high speed) until the oil refils. It has also been suggested that the return spring is too weak to operate basically a manufacturing/design issue on early models (2002 - 2005)...
There has been many postings on this site over the years about this issue...and many have had repeated dephaser failures.

The part has now been redesigned a couple of times to overcome the issues...the latest version should be fitted to 2006 onwards, so in theory there should be few failures on 06 plates onwards (unless you know different ?)

How to Change
This is a skilled job and not really possibly for the home mechanic unless very experienced.
It requires locking the cams, changing the cambelt and removing the front cam very easy to knockout the timing, best left for a mechanic.
cost of dephaser part is £ with cambelt and labour it's going to be £350+ from a back street...up to double from a main dealer, a renault independant will be somewhere in the middle.

here's a link to a thread that explains the issue with pictures and advice on DIY viewtopic.php?f=2&t=8033&

Diesel Glow Plugs
see viewtopic.php?f=2&t=8224

Water Ingress
The megane is poorly water proofed...getting water into the electrics is a bad thing and will result in many different issues.
Problem areas are...
front doors...where the speakers are located water can get into the car result in water in the door and floor pockets and wet carpet.....The speakers need to be resealed in the door pocket or add a better inner door skin.

electrical failures and poor running seemingly unrelated to each other.... windows going down instead of up, auto lights not working...battery discharging itself...wipers not working etc etc.

Possible Cause
missing cover in the nearside wheel arch (for changing the headlight bulbs)..and water entering the UCH electrical unit.
ensure the cover is not missing and is well sealed..can be expensive if the UCH is corroded by water damage.
basically water & electrics don't mix.

"The PSU in your car became flooded with salt water. It is corrosive and dissolves printed board circuit (PCB) tracks and connector pins. If they are still intact and the failure is due to the leakage current, then the only escape is to remove the PSU, wash it with water, dry it at +60C (which is significantly lower than the limits of the components) and put it back. It would be also wise to remove the PCB and spray it with 3-5 layers of urethane." - source Alexb

Water in the engine fusebox, UCH, ECU...The fusebox lid is badly designed on early models and can let water in. This is fatal and can result in a new fusebox and drying out the ECU and other electrical bits..expensive.

Water can also lie in the bulkhead and you will hear the water "sloshing" when turning left/right...The water can make it's way thru the bulkhead into the cabin through cable holes...To resolve the drain in the bulk head will be blocked with dead leaves. see viewtopic.php?f=2&t=12727

Window Regulators/Motors
A very common failure is the windows to drop drown on their own. this is a failed window regulator. Again the most common reason is water getting into the inner door skins and into the electrics of the regulators/motors

Keycard Issues
the keycards are not very robust and can fail due to internal soldering drying out. See this guide on how to carefully prise apart the keycard and resolder the suspect parts.

original post below.....
maybe it's because it's a wet monday morning... but i just can't be bothered posting the same reply info to the same issues that ive posted many times previously over the past 18 months. why don't people use the search facility ?

I don't think it would be too difficult to search and collate all the best nuggets of info on these and put them into one Sticky Topic.
worth the effort ?

Re: Common Issues - sticky ?

Posted: Fri Nov 28, 2008 12:18 pm
by chevin

v v v interesting thread.........I say so as if cars suffer from common faults then these are/could be construed as "manufaturing defects" unde rthe 1979 Sale of Goods Act.

Even OUTSIDE any warranty manufacturers (of anything) are obliged to fix these foc ! Some people (!!!!!) could use this kind of thread as eveidence that where they have such problems (dephaser etc) the car was not of "satisfacory quality" when it was made and they have a claim.

Suppose we had a thread on each topic and thousands signed up to say they had a problem with this aspect of their car - this could be used in evidence in the small calims court that....these cars are a pile of you see where I coming from and where I'm going?

Re: Common Issues - sticky ?

Posted: Wed Jan 07, 2009 9:43 pm
by jo3yb777
my megane often has that grinding noise
always thought it was something to do with the gearbox
but i now know my dephaser thing needs changing

thanks very much for the post :D

Re: Common Issues - sticky ?

Posted: Tue Jan 27, 2009 10:25 pm
by mattloftus
One thing I'd like cleared up is do I NEED a dephaser in the first place? In other words is it worth me spending all that money on something most mechanics have never even heard of, or do I just put up with the occasional bag of spanners symphony when i start my car? Will there be any potential damage by not having it replaced and just putting up with it until i sell it?

Re: Common Issues - sticky ?

Posted: Thu Jan 29, 2009 7:49 pm
by markren2004
I guess the answer is it depends on how bad it might get to a point where it won't start at all..and if it does the normal MPG will drop if it's not working correctly, so might end up costing more in fuel than if you fixed it in the first place ?

Re: Common Issues - Read this first

Posted: Wed Apr 29, 2009 6:00 pm
by tamarisk
I for one would add my name to a central list of common manufacturing problems, I have the dreaded water ingress problem, car has just been back to Renaults, 2 broken wires fixed apparently and advised that rest of the wiring is in poor condition as though it has been left open to the elements- NO! it's bloody water getting in because the car wasn't sealed properly in the first place! Also had the nightmare of having to change an indicator bulb-Absolute Madness! To be honest I just want to get rid of the thing, unfortunately after 3 days being advertised I've not had a single enquiry. All I can see ahead money and problems!

Re: Common Issues - Read this first

Posted: Fri Jun 05, 2009 7:53 am
by binclintonusa
I have the dreaded water ingress problem, car has just been back to Renaults, 2 broken wires fixed apparently and advised that rest of the wiring is in poor condition as though it has been left open to the elements. :o

pret auto

Re: Common Issues - Read this first

Posted: Sun Jul 26, 2009 10:55 pm
by swordfishtrombone
2004 Renault Megane 1.6 Expression 5 Dr- PETROL

Hiya all! I'm not sure where I should put this message so decided not to make a new thread since this one has starts with some excellent points!

First off I bought my car 8 months as a damaged car. I have been told it should have been a class c damaged car (if it was actually recorded) and written off from a previous front end accident.
All the bodywork and fittings have been corrected and the only thing left remaining is to replace the dash airbag and rear seat belt pretensioners and a new ecu (reluctant atm since just how expensive people people are selling parts/kit for.

The car has been absolutely sound it's such a smooth ride and is my second car after my Megane Mk1!

Although due to the cold weather over winter the car has magically decided to short and I have to jump start it many times from another car and let it tick over securely at the back of the drive. I replaced the standard battery with a good halfords spec one. Still this happens to it ever so often and is inconvienient when you decide to drive and is flat!!
Battling on with this, I keep guessing the airbag system is zapping the battery supply until they are replaced. Obvious one would say.

Since this has started continued the car decides to go into 'limp mode' (or at least what it could be reading on here!) where it decides after heavy hill climbing to stall when stationary and the engine is really sluggish after cooling down coming back to it, it's either flat again or simply working again (limp mode??)

Reading from all the things on here could it be the pencil sensor/coils telling the car to enter limp mode?

-The car has extremely low mileage- 19 and a half miles!!

-I have cleaned the earth points throughout the car.

-Lambda valve??

-Fitted at one stage a aftermarket stereo- uninstalled it upon first symptoms.

-The petrol flap has no power actually going to and so the central locking won't open the flap and remains open (possibly the airbag system saying to open in the case of a major accident?! and emergency services need access to it... at least that's what I guess!)

-Had the alternator checked said it's okay.

-I'm no mechanic or auto electrician neither. But my dad knows much to a degree!

-This happens when it's hot or cold.

I'm absolutely fed up with this now, it's a lovely car but now too much grief.
Thanks guys :-)

Re: Common Issues - Read this first

Posted: Thu Sep 03, 2009 12:12 pm
by dougsinnott
I bought a Renault Sport Tourer 55 plate 1.5dci Auto ( a very rare car!),in November last year,for £5995.
It had full Renault service history,and was an ex Motability vehicle,with only 29000 miles only on the clock.
So,theoretically,it should be almost as new,and mechanically and electrically reliable.
Previously I'd owner 2 Citroen C3s,and a Citroen Picasso mpv,without any problems.
On the face of it the Renault seemed good value,and I liked the extra room after my previous auto Citroen C3 (52,000 problem free miles).
Almost immediately,however,the Megane started to go wrong,with squealing front brakes,and a jerky gearbox,but it had a 3 month warranty,so I wasn't too bothered.
The Independent dealer,Tottington Motors,(who were worse than useless,so beware!)in Bury,Lancashire,looked at the brakes(or so they said),and checked the gearbox,and said they were now Ok.
They obviously didn't do anything,as the problems persisted,so I booked it in to my local Renault dealers,Arnold Clark,in Gemini,Warrington,as the gearbox had become dangerous,refusing to change to top gear on the motorway,so at one point I was driving at 70mph in 3rd gear!
Renault quickly diagnosed the problem,as a faulty gearbox sensor,and as the car was less than 4 years old,Renault offered to pay 50% of the repair cost,the other 50% Tottington Motors agreed to cover under the warranty.
The gearbox is now fine,but then I started having problems with the lights affecting the engine speed when I put them on!Also,when I braked,the lights came on,so drivers ahead thought I was flashing them!
Back to Renault(who have proved to be an excellent Franchised dealer),and a brake switch was replaced.By now the car was out of the 3 month warranty,so that cost me £40 or so.
They also did a safety check and they warned me the rear brake discs were corroded,and would require changing in the near future(after only 36000 miles!!)
Not good!
At the same time I had the car serviced,and they also changed a headlight bulb.
The squealing brakes I attempted to fix myself,by smearing copper grease on the back of the brake discs,and it worked for a while.
Also,in addition my car rear bumper was scraped in a car park,and i had to get it repaired,at a cost of £150!
Then,on Sunday,my driver's window now refused to open,and I had to replace the stop light/tail light bulbs,which seem to have a tendency to work loose from the holder.Also one taillight was brighter than the other!
I booked it into Arnold Clarks again,but I also contacted Renault Customer Services and expressed my disatisfaction with reliability of my car.
They got back to me the same day,and they couldn't be more helpful.
They fully sympathised with me,agreeing such a low mileage car,which had been fully serviced by Renault Dealership,should not be giving me these problems,and have agreed to cover the costs of repairing the window,and,possibly,sorting out the electrics,and my brakes(as they were squealing again).
I don't really wan't to change my Megane,as it is economical,comfortable,roomy,(but the cost of a new timing belt is scary!)and the Flame Red paintwork is really nice,but any more problems,and reluctantly I will have to get rid of it,and look elsewhere,and not at a Renault!

Re: Common Issues - Read this first

Posted: Thu Feb 18, 2010 9:02 am
by R55VYS
Just had the window reg break on me monday morning, after finding out its a £300 fix i set about trying to fix the problem for the mean time.

I think you should maybes add a quick fix to that link so that people dont need to use a binbag to cover the window.
Basically if you remove the reg from the white plastic triangle it frees up the cables so that the window can be pushed up and something placed beneth to keep the window up. its a fairly simple task once the door card is off and saves alot of chew, something renault wont tell you, then its a quick trip to the breakers and £40 for a reg as apposed to £200 plus labour from renault.

Re: Common Issues - Read this first

Posted: Fri Feb 19, 2010 9:59 pm
by ceiro1
Hi All, I bough a 2006 Renault Megane 1500 dci dynamiqe in June of last year - the wife and I had always liked its looks. However from day one this car has been nothing but trouble - severe water ingress in the boot,failure of dashboard lights, failure of starter motor, failure of fuel pipe to engine resulting in a major leak - has anybody else suffered these kinds of failures? I was less than impressd with Renaults response to these faults and they tried to dodge the issues untill the car was finally out of warranty.
On the plus side the car is very livley (106 bhp) and returns excellent economy - unfortunatley though as it has been so unrelaible (on average 2 faults per month since ownership) we have decided to cut our losses and are in a heated debate with the finanace company and suppliying dealer.

Re: Common Issues - Read this first

Posted: Wed Mar 03, 2010 2:34 pm
by AlexB
Index of Manuals and Technical Notes


Re: Common Issues - Read this first

Posted: Thu Apr 15, 2010 9:27 am
by markmetcalfe

my megane turns over but wont fire up.

there are no warning signs on the dash and cant smell excess petrol.

any ideas?


Re: Common Issues - Read this first

Posted: Tue Sep 07, 2010 6:31 pm
by adeathome31
ive had the wet fusebox problem on my 2004 1.5 dci megane estate.had to have new one fitted.put rubber mat on top to stop water from wing which has no runner to direct rain away.had drivers window repaired,back one doesnt work.only had car 5/6 weeks and not impressed at al with renault engineering.i new i should have bought that merc more renaults.

Re: Common Issues - Read this first

Posted: Thu Dec 16, 2010 9:35 am
by kenster
Honestly i have to say never in my life have i come across such a confused automated car.

It winds down one of the windows on it's own weve had it disconnected for the moment - is this the regulator issue?
Most of the time the headlights are on even in midday sun,
Eats headlight bulbs ive changed about 4 now.
Indicators keep losing connection, a complete PIA how do i get to the connectors. I keep having to shove my hand up the back of the wheel arch to just reach and twiddle the back of the connector.
Wipers come on/off whenever they feel like it.
Try n wash the rear windscreen, washes the front.
Sometimes all 4 tyres have punctures and im going to die "STOP!!" Sometimes i only have one flat tyre.
When i run low on fuel (say below 30mile range) it refuses to give me any more detail like a petulant child!

And may i add 6th gear is like 4th gear in my A3!!!
Mechanically the car is ok, electrics are a complete funking disaster. Who the fck managed to design such an abortion without finding all these problems?

I did read somewhere else someone saying sell your Megane before it bankrupts you!!! I thought this car was great, its a smooth ride and handles well, although the 2.0 engine is massively dissapointing with zero low end torque and unhappy about revving to 6k.