FAILING PENCIL COILS

Symptoms include engine misfiring, rough running and possibly a smell of unburned fuel. The fault lies with the pencil coils and the trouble usually starts with an occasional cough from the engine. It’s only when a coil fails completely that the car will become undriveable, and because of the engine set-up it usually takes out two cylinders at once, ie, cylinders 1 and 4 or 2 and 3. You will certainly find a trouble code stored: ‘P0301’ denotes cylinder

1, ‘P0302’ is cylinder 2 and so on. If possible, a full diagnostic check should now be carried out, but be aware that cylinder 1 on Renaults is on the gearbox side. If no diagnostic tool is available, a quick check can be to disconnect each cylinder injector in turn and listen for a change in the engine tone.

The coil is held in place by either a 10mm bolt or Torx bolt. Be careful when refitting these: they should only

be done up hand-tight and the threads strip easily. If the threads do strip it’s a nightmare to get to them.

It’s always worth renewing ALL the coils at once as they are very cheap and usually fail quickly, one after the other. It goes without saying that it is also wise to replace the spark plugs at the same time.

Note that a plug and coil covered in oil indicates a worn cam cover gasket; this should be renewed at the same time.

CRANKSHAFT SENSOR PROBLEMS

When our next fault arises, the engine may intermittently refuse to start, only to fire up at the next attempt. Unfortunately, there is no set no pattern as to when the car will or won’t start! This frustrating fault can be difficult to

diagnose and it’s hit-and-miss whether a diagnostic fault code will be stored, but you might get a code relating to the crankshaft sensor or engine speed sensor. A quick test is to locate the crank sensor above the gearbox, wiggle the wiring and then try to start the engine. Dodgy wiring to the plug is a common problem, but the crankshaft sensor itself can also fail – it’s held in place by two 10mm bolts, but be very careful when removing it so that it doesn’t fall inside the gearbox.

If you have an appropriate diagnostic tool, another test is to look at the live data and check for an rpm signal, which will put you in the right area.

There is a modified sensor and connector that needs wiring in with a new plug. The kit comes with a crimptype connector, but we have found in the past that it’s best to solder the connections because the crimp-type can corrode around the joint. It is also recommended that a good spray wax or silicone protectant is applied afterwards.

A new sensor/kit is readily available at all motor factors, but avoid cheap or poor quality brands.

FAULTY WINDOW REGULATOR

This ailment isn’t exclusively a Mégane fault but something that plagues all Renaults of this era. As with the ignition coil fault, if a car has been owned for more than just a very short time, the owner/operator is very likely to have suffered from this.

The fundamental problem lies with the electric motor, which has a habit of failing out the blue, with the result that the windows get stuck in the ‘down’ position.

Fortunately, removing the door panel to gain access to the electric motor is simple, although the panels are held on with Torx screws and some infuriatingly poor quality plastic clips which generally break when removed. A new motor is readily available from aftermarket parts suppliers, and it’s not really worth paying extra for a genuine Renault part.

Another annoying problem is a troublesome hazard lights switch. These fail internally and when the switch is pressed, nothing happens. This fault requires the fitting of a new switch and affects the entire Renault range.