[redman]

Hi
There was a recall to have the upper oil switch removed.
Also oil can travel down the wiring loom from the oil pressure switch in to some of the sensors plugs ( 02 sensors etc) causing the engine to misfire.

 

[redman]

Is it the upper oil switch you are talking about?
Oil can get in to the wiring plugs through capillary action. So I would unplug some and look for signs of oil. So it can cause misfiring.

 

[redman]

It is not so much oil leaking on to the electrical plugs exteriors as the plugs have ingress protection seals. It can be capillary action through the inside of the cables.
You should try to get the engine fault codes if any are present and at least fit a new oil pressure switch. Then you can look into getting it blanked off and the single core cable insulated.

Here is a link for oil contaminating the wiring on a 1.4 ecotech engine through the pressure switch. I know yours is the1.6 and there won't be many cases of it happening to that engine (as the upper pressure switch was removed in production or on a recall).