My TJ 3.5 (225,000km) has been getting pretty rough starting over the past few months - when it's cold, it usually kind of stutters into life. Once it's actually started, no problems at all, it drives perfectly. Just to confirm, plugs, leads & dizzy cap are all pretty new.

Then recently, the engine warning light (the amber one that's an outline of an engine) has been coming on. Not all the time, but quite frequently & once it's on, it stays on until the engine is turned off. I understand from the manual that this is an indication of a problem with the emission control system, but it doesn't say what that might be.

Before I take it in to a dealer, does anybody know what particular issues could cause the warning light to come on, & could it be related to the starting issues?

You need to check the codes. the engine light could come on for any number of reasons. Take it to a dealer and check which code it is then refer back to us and we can tell you how to fix it

Alternatively ground the first connector on the diagnostic connection plug and diagnose the problem yourself. The plug is located near the centre console on the drivers side. You need to stick your head under the kick panel. The pin that needs to be grounded is the first pin from the left on the top set of pins.

Once this is grounded properly, the engine light will flash. Do a search. There are plenty of threads on this forum explaining how to read and interpret the flash intervals and it'll give an indication of what the problem may be.

Alternatively ground the first connector on the diagnostic connection plug and diagnose the problem yourself. The plug is located near the centre console on the drivers side. You need to stick your head under the kick panel. The pin that needs to be grounded is the first pin from the left on the top set of pins.

Once this is grounded properly, the engine light will flash. Do a search. There are plenty of threads on this forum explaining how to read and interpret the flash intervals and it'll give an indication of what the problem may be.

Agreed. Take care that you get the right codes. Many dealerships will test it for nothing/very little if you are not comfortable with this option.