Engine management warning light

A few weeks later: After standing for 3 weeks ( in workshop being derusted and having the underside sealed) and me away in Munich, on my return... slight rough running and the EM light came on, as you all said it would.

I have received my diagnostic tool (V311 OBD2) and found the OBD2 port (drivers side, under dash, right hand side) and diagnosed sporadic cylinder misfire on all cylinders. Lots of other info too, but that is for the weekend when I will look and learn. So the Jimny is booked into a garage next week to see what gives. My hopeful feeling is that the Wynns engine cleaner has loosened gunk which has affected the fuel injectors. Lets see.....

A tired battery can cause a weak spark and lead to rough running, especially if something else is on the way out (like coils/plugs) so if it has been stood for a while, I I would charge your battery and see if some of the codes will clear?

If the misfire goes, it might suggest coils or plugs are ageing, look for cracks in the coiul packs.

You were absolutely correct: spark plugs and coil need replacing. Being done for me as we speak. Will get the vehicle back tomorrow and go for long run on the weekend. I hope the dreaded EML does not come on again!.

If you did have a weak spark, new coils and plugs will not only get rid of the EML, but it will feel like a different car.