I have a Citroen C4 1.6 petrol (2006) and the other day while I was driving the engine light came on with a message "Depollution system faulty". I connected the OBD-II to my computer to get the error code and it was P0350.

From that error I think my option would be that a wire is loose or something, because I didn't feel anything weird while driving. The problem is that I don't know where to look in the engine to check the cables are properly attached.

  • Did you try to clear the code? If so, did it come back? Sometimes a code will pop without there really being a problem. If the car is still running well, it isn't a coil pack at this point (doesn't mean it didn't hickup and it might be on its way out). If it were a coil pack, it would be running like dog poop, especially considering it's a 4-cylinder engine ... then a 4-cyl which probably doesn't have a lot of giddyup in the first place. Commented Jul 24, 2014 at 0:02
  • Well @Paulster2, yesterday I look at the ignition coil to see if the cable was loose or something, and it wasn't.. but the I tried to start the car and it took me 3 tries before it actually turn on.. so I think I will replace it.
    – SERPRO
    Commented Jul 24, 2014 at 9:06

1 Answer 1


This code means you have faulty wiring/coil pack. Usually means a new coil pack. To find the coil pack, look at the top of the engine. Between the engines top cover and its manifolds, at the rear, you will see a manifold wide black block. It has a grey plug entering it from its right hand side. (Viewed from the front of the vehicle). This is your coil pack.

  • I changed the ignition coil pack and after a day I got the same error again on the OBD-II. Any ideas?
    – SERPRO
    Commented Aug 5, 2014 at 11:52
  • The fault code you have given P0350, is for a fault on the primary or secondry windings on your coil pack. The spark plug should also be considered as part of the secondry windings. The wiring on the coilpack plug and the coilplug plug itself must be clean and sound and not leaking electrically. Remove the sparkplugs and examine them for cracking and any sign of arcing, (leaves a black dusty deposit). Also make sure you are not getting oil gathering in and around the spark plug hole. Commented Aug 5, 2014 at 13:19

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