Code P0304 HELP

[KingCloudIX]

Hey everyone,

I apologize before hand if I am posting in the wrong place. I am new to posting but I have been reading the forum for a while.

I recently bought a 2010 335XI a couple months back and the SES light came on yesterday. I took it to auto zone and the code reader popped up P0304. After doing some research here I found that the first step to take should be swapping coils and then moving on to changing spark plugs if the code does not follow the coil swap. From reading another post, the op ended up using a fuel injector cleaner and the code went away although he did change spark plugs and performed coil swap. My question is, would adding fuel injector cleaner clear the code? Should I add the cleaner first and then move on to coil swapping and spark plug changing? The car does not seem to misfire at all and sometimes has a rough idle for a second but the rough idle used to happen before SES popped up. Car has about 37000 miles.

[d21spike]

Hey everyone,

I apologize before hand if I am posting in the wrong place. I am new to posting but I have been reading the forum for a while.

I recently bought a 2010 335XI a couple months back and the SES light came on yesterday. I took it to auto zone and the code reader popped up P0304. After doing some research here I found that the first step to take should be swapping coils and then moving on to changing spark plugs if the code does not follow the coil swap. From reading another post, the op ended up using a fuel injector cleaner and the code went away although he did change spark plugs and performed coil swap. My question is, would adding fuel injector cleaner clear the code? Should I add the cleaner first and then move on to coil swapping and spark plug changing? The car does not seem to misfire at all and sometimes has a rough idle for a second but the rough idle used to happen before SES popped up. Car has about 37000 miles.

Very high probability the injection cleaner wont do much for you if it's an injector issue. More often than not when these cars have injector issues, the injectors leak eventually leading to potential washing of the rings. I'd start with what you mentioned, move coils first. If that doesn't change anything, try new plugs. After that, you can check the injector index number and go from there.

[KingCloudIX]

So I ended up taking the car to the dealership for a diagnostic since I do not have the time or tools on hand to swap the coils and check spark plugs. Sooner than later I will buy a set of tools. The dealer found that the car was leaking oil and the index number on my injectors were below 11. They told me I need a new valve cover gasket, replace oil filter housing, and 6 new injectors. I just bought the car a couple months back and had no idea all this would happen so soon if at all. I am learning more about the car as I go. My question is, do I need to replace all 6 injectors at once when going index 11 and up or can I change 3 at a time ie Bank 1 and then Bank 2? The car has 37k. If I absolutely must replace all 6 at once, is there anyplace I can buy the older injector? What is the difference between injectors with index below 11 and above 11. Do they fail at the same rate?

[d21spike]

OK well first since you're not capable (yet) to work your car, I would begin with finding a quality independent mechanic to do your work. The dealer will leave you hating BMW. The valve cover gasket leaking is common but also keep an eye on the valve cover as they are known to crack also. Are you sure the oil filter housing needs replaced and not just a new gasket set? Seems a bit excessive. In regards to injectors, yes you can replace them in banks and they will need coded. On that note, keep in mind they can leak and result in more costly repairs so would you want to save money now to spend more later? It will be rather difficult to find older injectors now and I do not recommend it. To buy the newer ones, people have been having luck with RockAuto and they believe that they are OEM for a fraction of the cost. Myself personally, I bit the bullet and bought BMW ones for the peace of mind. Failure rate is a big difference between old and new. Also, I believe there was a change in vendors. Either was you end up with a more reliable injector.


So I ended up taking the car to the dealership for a diagnostic since I do not have the time or tools on hand to swap the coils and check spark plugs. Sooner than later I will buy a set of tools. The dealer found that the car was leaking oil and the index number on my injectors were below 11. They told me I need a new valve cover gasket, replace oil filter housing, and 6 new injectors. I just bought the car a couple months back and had no idea all this would happen so soon if at all. I am learning more about the car as I go. My question is, do I need to replace all 6 injectors at once when going index 11 and up or can I change 3 at a time ie Bank 1 and then Bank 2? The car has 37k. If I absolutely must replace all 6 at once, is there anyplace I can buy the older injector? What is the difference between injectors with index below 11 and above 11. Do they fail at the same rate?

[KingCloudIX]

OK well first since you're not capable (yet) to work your car, I would begin with finding a quality independent mechanic to do your work. The dealer will leave you hating BMW. The valve cover gasket leaking is common but also keep an eye on the valve cover as they are known to crack also. Are you sure the oil filter housing needs replaced and not just a new gasket set? Seems a bit excessive. In regards to injectors, yes you can replace them in banks and they will need coded. On that note, keep in mind they can leak and result in more costly repairs so would you want to save money now to spend more later? It will be rather difficult to find older injectors now and I do not recommend it. To buy the newer ones, people have been having luck with RockAuto and they believe that they are OEM for a fraction of the cost. Myself personally, I bit the bullet and bought BMW ones for the peace of mind. Failure rate is a big difference between old and new. Also, I believe there was a change in vendors. Either was you end up with a more reliable injector.

I am not sure about the new gasket set. I actually looked this morning and there was oil coming from the side of the gasket so maybe this is so? It seemed like fresh oil and maybe explains the wet bottom. Oil level still fine btw. I have pictures and will try to post. Yes I saw the ones from RockAuto and I read about them as well. They seem like they will be ok from what people are saying. Especially since I am not modding the car in anyway performance wise and I don't necessarily drive it hard a lot. Plus if they fail they have warranty and would cost about the same amount (1 oem replacement vs 2 standard replacements). What do I need to code them? I saw this cable http://www.amazon.com/INPA-DCAN-Diagnostic-Cable-Interface/dp/B008MY1F8W but it says until 2008 models. Where can I find the software?