[JJ312]

anybody had experience with P0306 fault code? (Cylinder 6 misfire detected)

check engine light pops up every once in a while during idle, when I turn on the ignition in the morning.
(it's not super cold weather yet. and my car is always parked in a basement garage)

also there seems to be some tappet noise during idling.

my M2CP is completely stock with only 6,000km on it (approx. 3,700 miles)

I wanted to take to the dealer and have them scan it,
but apparently it'll be about 20~30 days before there's an opening....

any thoughts on what the problem might be and how to fix it?
1. check engine light P0306 fault code
2. tappet noise at low RPM (during idling)

thanks

[Tag]

If you've filled up with a fresh tank of fuel and it doesn't go away it's likely a bad spark plug or injector. You can start by swapping a plug from a good cylinder with cylinder 6 and if the issue moves to the other cylinder it's a bad plug. If however it stays on cylinder 6 it may be a bad fuel injector.

[DVG 335]

Originally Posted by Tag

If you've filled up with a fresh tank of fuel and it doesn't go away it's likely a bad spark plug or injector. You can start by swapping a plug from a good cylinder with cylinder 6 and if the issue moves to the other cylinder it's a bad plug. If however it stays on cylinder 6 it may be a bad fuel injector.

It could also be a bad coil pack. Swap the coil pack and spark plug with different cylinders (e.g. move coil from 6 to 4 and plug from 6 to 5) and see which cylinder the misfire moves to. If it stays at 6, it could be an injector or something on the top end of the engine.

[Tag]

Originally Posted by DVG 335

It could also be a bad coil pack. Swap the coil pack and spark plug with different cylinders (e.g. move coil from 6 to 4 and plug from 6 to 5) and see which cylinder the misfire moves to. If it stays at 6, it could be an injector or something on the top end of the engine.

Indeed, forgot to mention that. Usually in order of checking it's spark plug, CP and then injectors.

[CanadianComp]

I had the same misfire code come up on my brand new M2C as well...

Same situation for me as well, on cold startup (in heated parking garage), as the idle is settling I noticed some irregularity, the idle almost pulsed which I believe was the misfire.

I booked it into the dealer, but of course the code went away when I fired it up that day and dealer said to just monitor it and see if it comes back...

It hasn't come back and that was a month or so ago so

Also, I did take it in for break in service after this happened, forgot to mention it to them before hand but asked afterwards and they just said tech didn't notice anything.

It still has the odd pulse (misfire?) on idle though...

[JJ312]

Originally Posted by Tag

Indeed, forgot to mention that. Usually in order of checking it's spark plug, CP and then injectors.

thanks, I'll def. try out what you mentioned above.
sounds like a weekend project

[JJ312]

Originally Posted by CanadianComp

I had the same misfire code come up on my brand new M2C as well...

Same situation for me as well, on cold startup (in heated parking garage), as the idle is settling I noticed some irregularity, the idle almost pulsed which I believe was the misfire.

I booked it into the dealer, but of course the code went away when I fired it up that day and dealer said to just monitor it and see if it comes back...

It hasn't come back and that was a month or so ago so

Also, I did take it in for break in service after this happened, forgot to mention it to them before hand but asked afterwards and they just said tech didn't notice anything.

It still has the odd pulse (misfire?) on idle though...

engine fault code went away by itself?? that's weird....

I've been doing some research on S55 engines, and there's a split opinions whether it's normal or not.

it's not just on cold start I noticed the tappet noise.
even after I get home from work (including about 20mins of highway), I can still hear the noise

[bri1042]

I had the same issue early on. They pulled and tested the plug and coil pack, everything came back OK. They put it back in and it's never happened again...12k miles since.

[JJ312]

Originally Posted by bri1042

I had the same issue early on. They pulled and tested the plug and coil pack, everything came back OK. They put it back in and it's never happened again...12k miles since.

new plug and coil pack wasn't installed?
maybe mine is just slightly loose then....

[bri1042]

Originally Posted by JJ312

new plug and coil pack wasn't installed?
maybe mine is just slightly loose then....

Nope, they didn't end up replacing anything. I was a bit annoyed at the time, but that was 12000 miles ago and it's been fine. I was checking codes a lot for a while afterwards, and still do check every once in a while.

[mzvertigo]

My 2020 M2C (only 8900 miles) is at the dealership now with misfire issues. The SA confirmed that the technicians found faulty injectors in cylinder 1 and cylinder 3 and replacing them under warranty.

Not very reassuring though that an 8900 mile car has 2 faulty injectors already (though the car was being driving spiritedly on weekends and has seen 2 track days with a few about a year's gap between them)...

[rcouchh]

Just dropped of my M2C today at the dealer for a misfire code. CEL has been coming on and off since I got the car 2 months ago. It randomly comes back on when I first start the car and will go away after a couple hundred miles. First and second time I took the car to the dealer for this issue, they told me it was because of a bad gas cap lol.

This time they are actually taking it apart to determine the real issue. Annoying my brand new car has been back and forth to the dealer 5 times now since I bought it. Nonstop taillight failure issues, then they put a deep scratch in my bumper and repainted the whole thing, now CELs, etc.

[mzvertigo]

Originally Posted by rcouchh

Just dropped of my M2C today at the dealer for a misfire code. CEL has been coming on and off since I got the car 2 months ago. It randomly comes back on when I first start the car and will go away after a couple hundred miles. First and second time I took the car to the dealer for this issue, they told me it was because of a bad gas cap lol.

This time they are actually taking it apart to determine the real issue. Annoying my brand new car has been back and forth to the dealer 5 times now since I bought it. Nonstop taillight failure issues, then they put a deep scratch in my bumper and repainted the whole thing, now CELs, etc.

Dang...that sucks that this has been repetitive for you. Have they done anything on any of the previous trips for the CEL or is this the first trip for this particular issue?

[rcouchh]

Originally Posted by mzvertigo

Dang...that sucks that this has been repetitive for you. Have they done anything on any of the previous trips for the CEL or is this the first trip for this particular issue?

3rd time I've taken it in with the same misfire CEL. First time they claimed it was just because of the gas cap that didn't seal, said the "gas vapors" escaping would cause a misfire. I called BS but they told me it was fixed. Was obvious they just wiped the code but didn't actually do any looking into it.

CEL came back the next day, they didn't have an appt available for another week so after driving about 150 miles the light went away on its own. Was back at the dealer for the rear taillight failure later on, and with my bad luck the CEL went away the morning I took it in. They said they'd investigate the misfire reoccurrence but clearly did nothing again.

Guessing its just an injector or coil pack or something. Funny since this time I had a new service advisor, I mentioned what they told me about the gas cap causing it and he was like "yeah there is no chance that would cause a misfire". Car was at the dealer all day today and they didn't even get around to even reading the code yet.

Had some pretty shitty experiences with BMW service dept's so far. Been to the dealer more in 2 months than my entire lifetime of owning 5+ cars. If I hadn't already started modding the car (just exhaust and cosmetics) I probably would've tried to get it declared a lemon.

[rcouchh]

Update on my misfire code as I've heard back from BMW. Car has now been with the service dept for 7 days and still no ETA of when I'll get it back. Getting pissed...

Misfiring on cylinders 1,3, 6. BMW of NA got involved, and advised them on steps to take. They had them check all engine grounds, get engine to temp and watch engine values, removed spark plugs and looked into cylinders with borescope. Found a vacuum leak, so swapped intake tube. Swapped all plugs/coils, and now are supposed to replace the fuel injectors next.

BMW of NA sent an engineer down, he said he ran tests and will be in contact with the dealership on Monday on what to do next. My service advisor said he has no clue why BMW of NA is so involved with this specific instance, and that he in the dark as to what they're doing. Starting to worry me a bit, especially because this issue was prevalent when I first bought the car 2 months ago (it was a used 2019). I'm sure the other dealership I bought it from knew about it, as well as the previous owner.

In 2 months of ownership, my car has now spent roughly 3 weeks in a service dept total. Pretty sure that classifies as a lemon.

[nearwater4me]

I had 3 DTCs come on one night :
- Multiple, random misfire
- P0302 : cylinder 2 misfire
- P0304 : cylinder 4 misfire

Emailed my dealer asking if it has anything to do with the recent spark plug change service.
Dealer told me to clear the code and see if it returns.
Did as told, and it hasn't returned so far.

[M2 CCO]

Had the same problem. Technician corrected in about 3 hrs.

[Slyphen]

Originally Posted by M2 CCO

Had the same problem. Technician corrected in about 3 hrs.

had the same exact issue.

[nearwater4me]

So, the CEL has returned after clearing it per dealer instruction.
Dropped off the car for diagnostics. Will report back with what they find/fix.

[Megator]

Originally Posted by JJ312

anybody had experience with P0306 fault code? (Cylinder 6 misfire detected)

check engine light pops up every once in a while during idle, when I turn on the ignition in the morning.
(it's not super cold weather yet. and my car is always parked in a basement garage)

also there seems to be some tappet noise during idling.

my M2CP is completely stock with only 6,000km on it (approx. 3,700 miles)

I wanted to take to the dealer and have them scan it,
but apparently it'll be about 20~30 days before there's an opening....

any thoughts on what the problem might be and how to fix it?
1. check engine light P0306 fault code
2. tappet noise at low RPM (during idling)

thanks

I had this code, coil 6 was faulty and the dealer replaced it under warranty.

Yours is still in warranty no? just take it to the dealer getting at the plugs is tedious.

[Kankles]

My bet it's a coil pack. A good way to diagnose (if dealer can't do it for whatever reason) is to swap the CP to another cylinder and see if the fault code follows to the new cylinder.

[nearwater4me]

Originally Posted by nearwater4me

So, the CEL has returned after clearing it per dealer instruction.
Dropped off the car for diagnostics. Will report back with what they find/fix.

Dealer replaced plugs for cylinder 2 & 4.
Hopefully it was just the plugs and not injectors.