Car turns over but wont fire?

[richydee]

Spend 4 hrs cleaning, machine polishing and waxing my temperamental french b**ch 😂 only for her not to start up 😢.
Got error p0303 on my little cheap OBD reader, this code is saying misfire on cylinder 3, doesn't the car need to be running for the misfire to occur?
Car was running great until today.
I been through some of the post on here and the majority have said the car was running poorly or didn't sound right!! that wasnt the case with mine...fekn frustrated with her but I,ve had her since 2007 and just spent a small fortune getting her stunning again..

Any help is appreciated.

 

[Pegasaurus Rex]

Did you wash under the engine bay at all? What symptoms do you have? Is the red immobiliser light going out when ignition is on? Is the car turning over? If so is it doing so comfortably?

 

[richydee]

Didn't wash the bay, engine turns over fine, will need to check immobiliser light🤔 (should it be on or off when keys in ijnition)
EML on p0303 error which I've cleared using my obd reader.

 

[Martin_172]

Check the immobiliser light, if it's going out as it should I'd turn my attention to the crank sensor