2004 Renault Scenic testing for a faulty ignition coil

Best to replace all 4 .

check that they are all producing a good spark,can also check resistance across terminals with a meter,all the readings should be approx the same,if any are down significantly then change it

the coil primarys are wired in series so 1 and 4 are together and 2 and 3 are together .try unplugging the fuel injectors one at a time whilst running to see if any do not drop the engine revs significantly the one that doesn,t will be the faulty coil,however this might put more fault codes in the ecu that will say injector faults and will have to be cleared

If I get a fault code reading injector fault does it have to be taken to a garage to be cleared or can I do it myself.Thanks.

I have replaced 2x ignition coils,when engine is ticking over I have removed the leads to each ignition coil and engine misses when removing each one which I believe is telling me that all ignition coils are ok.
On a test drive the car has no power at all when cold but is ok once engine warms up.
Please can you help.