A couple of weeks ago I pulled off the road to find a business on my phone. I went ahead and turned the MINI off while I looked on my phone for a few minutes. I turned the car on, and the ACS light and "Service Engine Soon" light both came on. My thought was "Crud. I don't have time for this right now." I turned the car off and on, and the ACS light went off. I didn't mess with it, and three days later the SES light went off as well. A couple of days later I stopped for gas, and when I turned the MINI on afterwards, once again those same two lights came on. Once again, the ACS went off after restarting the car. A few days later…you guessed it, the SES light was gone. So, here I am a few days later, and those lights came on again. Only now the ACS light is staying on. Both lights are on every time I turn the car on.

I went to Autozone, and they read the code P0304 (cylinder 4 misfire). He said, "Wow! Your car must be running real rough!" Uh…it's not. It's running the same way it has for the past eight years…Awesome!

I bought spark plugs thinking I would start there. However, I just replaced the spark plugs a year ago. I haven't installed them yet. I'm thinking about taking it to the dealer and letting them diagnose this. This could turn into a wild goose chase. Thought I'd check here first and see if anyone else has dealt with this before.

 

If the ACS light came on then there's also an error code stored in the ABS module. Without reading this code too, you're definitely going on a wild goose chase.

 

Thank you, mrbean. So far I've replaced the spark plugs and the spark plug wires (which needed to be replaced anyway). That did not work. There aren't many other options at this point. I'm away from home for a couple of days, but my code reader won't read anything other than the engine. When I get back home I'm thinking I'll replace the coil pack and see what happens. If it's not the coil pack, it's going to be something truly expensive. :(

 

I replaced the ignition coil, and both lights stayed off during a test drive. It does seem to be running better as well. I'm thinking/hoping the issue is fixed.

 

UPDATE:

So I went about a week and half or so without issue, then both lights came on again. I decided to run Redline SL-1 through the system. Once again the lights stayed off for about a week and half. I've noticed that they come on every time I fill up with gas. It also occurred to me that I've been having this problem ever since I started getting gas at this station by work. (It's convenient. It's Conoco. And it's 100% gas.) Could the gas be causing this problem?

I've had the car for almost nine years, and I've loved it. …but I'm losing my patience with the MINI. Needless to say, this is frustrating. I'm going to order another code reader. (so I can read the ABS code) I'll get back on when I have more info.