Emission light comes on

it needs to go on a obd code reader/scan tool or suitable diagnostic equipment to help with this prob. could be lots of things, most likely lambda sensor faulty or catalyst fault. but could be other engine managment system fault like fuel pressure etc

You need to bring this to a pro, and make sure it's someone very familiar with Minis. possibly a bad converter, but could be a sensor or injection problem that is sending too much fuel down the line, making your post cat o2 sensor see trouble. Get after it quickly, and maybe you can save your quite expensive catalytis converter.

it isnt anything to be to worried about. it just means your not maintaining your car as much as you should be so its polluting more then it should be. Keep in mind that when you get the letter from your state to check your cars emission to see if it passes your states minimum requirements it will most likely fail and you will need to do everything to make it pass.
Examples: go to your focal shop most likely a jiffy lube does it the cheapest and best, ask for the fuel-injector cleaning. Its pricey but it will definitely help
Use better gas for a few weeks to clean out the engine. Such as BP or Shell
Change the Oil with more frequency so your car doesn't have to reuse old oil to run every 3,000-5,000 miles
change the transmission oil as well. This is also pricey but it doesnt have to be done as often as you think. Every 50,000-60,000 miles

Het it put on an ODB2 reader, it is likely to be an O2 sensor going wrong or something not too bad.

it could be the ignition timing or replace your fuel filter and the pvc valve and the air filter. Have you done to tune up your car? if not, tune up your car. If you done all of these you will see the different. ok

it simply sounds like your oxy sensor(s) are bad, maybe egr system, and or clogged catalytic converter. Yes it will be a little pricey. Sorry.

HAVE IT TESTED FOR TROUBLE CODES THAT IS THE KEY TO FIND THE PROBLEM.

The Exhaust Emission Light can come on if the car is driven slowly over short distances.It will not happen on cars driven at speed. A short trip of ten miles at over 3000 revs should reset the warning light,although it may not go out for a couple of days after you have tried it . Hope this helps and saves a bill at the local dealer. JK

Have the sedona scanned at an AutoZone or similar place and ask for code. they will not tell you whats wrong with it but they will give you a code. You can go from there. You can come back and tell us what the code is .

this may be your egr valve, does it want to stall when its ticking over.