Hi everyone,

i have a 2012 Cooper s (R56). I haven’t been driving that much lately due to the pandemic. Took it out today and got an amber CEL. The car also started to jerk a bit at low speed. I connected the scanner and it gave me the P0303 error code. I’ve been reading online about it, I could not find a good answer. The car is out of warranty, so I wanna try to fix it myself. The car only has 60k km.

i would like to fix it myself. Any advice please?

I really hope it’s not very serious.

 

Sure. There are lots of discussions about MINI misfires out there. To summarize: (A misfire in a single cylinder)

The first step for most folks is to swap the ignition coils from the cylinder 3 (in your case) to another cylinder. Takes < 10 min. The see if the misfire moves to with the coil. If it does; Rock Auto sells Bosch ignition coils for < $20.00.

If the misfire stays with the cylinder, you most likely have a bad (or intermittent) fuel injector, or you have a compression problem with that cylinder.

Now a professional shop will use a lab scope to further analyse your problem. The lab scope can detect in intermittent injector, and a skilled tech can perform a relative compression check at the same time. The relative compression check will give you relative compression between the cylinders; if one cylinder is low; you'll see it on the scope.

If it's the injector, you simply replace it. If it's a compression problem, then a leak-down test is required.

I've had two MINI (an '07 and my current 2012). The 2007 misfire I experienced was an intermittent #2 fuel injector. The 2012 I got off Craigslist for cheap because it had a misfire in cylinder 4; the bad part was the misfire was due to a hole in one of the exhaust valves. I'm putting the head back on the car tomorrow (all new valves.)

Let's hope you don't have one of these:

 

Thanks very much. I did as you suggested. I ran the scan tool
and I got p0300 and p0303. I swapped the 3rd and 4th coil and ran the scan again and got p0303( permanent code) and p0304 also showed up, but not p0300. Please see the pics.

So, if I understand you correctly, it’s my coil and just need to get one and replace the faulty one?

I also, noticed one thing. After I did the swap and started the car, I saw additional water droplets of water come out of the exhaust and bad smell like sulfur. Not sure, if that is related to this in any way. I checked the engine oil level and it’s good.

 

Ok. Let's backtrack a little. Can you clear codes with your scan too?

Did you clear the P0303 when you moved coils? If you didn't the P0303 will stay in memory until you clear it.

Now, how many miles are on the engine? How many miles are on the current set of ignition coils? See, these are coil-on-plug devices, and they get very hot! Some will recommend that you replace all of them at 100,000 miles. I do. A set of Bosch (the OEM supplier to MINI for ignition coils) is < $100 at Rock Auto.

Now on to your water droplets coming out of the exhaust and the smell. Engines breath air,;air has moisture (humidity) in it. That moisture condenses out during the combustion process; so it's normal to see some moisture coming out of the exhaust. When the engine reaches operating temperature that moisture turns into steam and is ejected with the rest of the exhaust gasses. The smell comes from the catalytic converter. It burns all the hydrocarbons (unburnt fuel) so they don't go into the atmosphere. So again, normal.

 

No, I didn’t try clearing the code actually before swapping and rescanning. I’ve never done that before, so I was a little apprehensive.

The app I’m using, has that option. I’m using an ELM 32 scanner. Do you suggest I clear the codes and swap them and rescan?

My car only have 38000 miles. Would you recommend I change all 4 coils?

Also, thanks for the explanation on the smell part.

 

Honestly might not hurt to swap all four plugs and coils. I swap my plugs every year, doesn’t matter the mileage, coils will be swapped end of this year unless I get a misfire earlier. I’m going to fcpeuro next time for parts and use the lifetime warranty for the replacements.

 

Yes, next time, clear the code when you move the coil and see what pops back up. 38K miles is very early to start having coil problems. There is no predictable failure pattern with ignition coils other that once they are north of 100K miles, failures are more likely. I would only change the one.

 

Coils are a complete crapshoot, in my opinion! They seem to be somewhat more reliable than they usually were 10 years ago, but not by much.

I know my statistics are weak here, but the one set of Dephi coils I bought died, one by one, over nine months time. Bought a set Bosch coils, 50K miles later they are still running fine.

At 38K the odds are that your plugs are, at the very least, tired. Replace them. I do a lot 90mph highway driving, both electrodes were usually badly eroded by 25K miles.

 

I think I’ll start with one coil at this point, since the issue seems to move from one cylinder to the other when I move the coil.

I think I need to drive the car more regularly as well. It’s been a garage queen for a while 😊

 

Turns out that the coil for cylinder 2 broken, but my scanner was giving P0303. Not sure why though. But all is well now. Engine seems to running smoothly.

can anyone recommend a good scanner?

 

There are lots of good scanners out there, so it depends how much you are looking to spend. What's your price range?

 

Was looking for something under $100, if feasible.

 

Email henry@foxwelltech.com and tell him Mark K (MINI Cooper Forum) sent you. Ask for an NT530. He'll give you a very good price.

 

I had one go out a couple years ago and just replaced the one. Haven’t had another fail yet at about 104k on my 2013. I suppose I should do the rest though.