Injector 3 circuit failure

[CalamatyC]

Recently, when towing, my 2015 Isuzu Mu-X 3.0L diesel went into limp mode. After stopping for about 10 minutes, the code disappeared and I was able to drive again a short distance, then the code reappeared. The engine felt like it was running on only 3 cylinders, and this was confirmed when I checked the engine code.
I left what I was towing on the side of the road, and was able to drive all the way home without the code reappearing.

When I checked the injector plugs, the plug to number three was loose, and came off easily. I pushed it all the way back on until it clipped into place, and everything seems to be working fine.
So I was wondering if anyone has any thoughts as to why the plug was loose in the first place.

At the time of there fault code, I removed the oil filler cap with the engine stopped,and there was a "smoky kinda mist" coming out of the filler cap, and I am not sure if that is normal or not. There was also a small amount of oil around the injector seal in the rocker cover, but that may have been nothing.

The last time the engine was worked on was when the valve clearance were done about 8k ago. Total engine Km's are only 57K.

Would be interested in any feedback.

Not sure if the copper seals on the injectors would be an issue, or something else. Any advised would be greatly appreciated.

Thank you.

[geeves]

My money is on the loose plug but only one way to find out. As for why it was loose. Its quite easy to have a plug snag on something and seem as if its fully plugged in when it isnt. The plugs might of been removed when the valves were adjusted or bumped.