Is this a misfire?
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Joined: Aug 2025
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From: Texas
2015 ML350, 2020 BMW X7, 2005 LS430
Is this a misfire?
Got a CEL on my ML350. Took it to autozone and they gave some codes related to the battery and also a p0306 code for cyclinder 6 misfire. I just replaced the battery and it's been giving some battery under-voltage related stuff. I don't know much about engines, but the guys at autozone said it probably was due to spark plugs and coils, but I put new plugs around 5k miles ago. I don't really hear a misfire, the engine's just loud cause it's direct injected. Could you tell me what you hear in the video below. Also the audio is a lot louder than it is in person, not sure why there's a lot more rattling in the video.
Last edited by ARL_350; Jan 3, 2026 at 05:23 PM.
Out Of Control!!
Joined: Nov 2018
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From: San Francisco Bay Area
2019 C63CS
No, that's not a misfire. The clicking is the high pressure fuel injectors. A distinctive sound of direct injection engines. An active misfire causes the CEL to flash. A flashing CEL needs immediate attention and best to shut off the engine as a misfire can cause damage to the catalytic converters if it goes on too long. A misfire also causes the engine to run rough, so it's hard to miss. However, a misfire can also be very brief and go unnoticed, other than the CEL staying on afterwards and if the misfire doesn't occur anymore for a period of time, the CEL will turn off by itself.
Misfires can happen for various reasons. Could be as simple as bad fuel or the fuel pump sucking in some sediments from the tank. Or it could be a coil that is on the way out. Could also be a faulty spark plug, even if they are brand new. Somebody with an E63 recently destroyed their engine after the spark plugs were changed. One of the new spark plugs was faulty and a piece of the insulator broke off and fell into the combustion chamber, destroying the cylinder. Luckily there's a 1 year warranty on parts and workmanship if the service is done at a dealership, so in their case Mercedes is covering a new engine.
The way to diagnose if it's a faulty coil, is to swap the coils between two cylinders and see if the misfire follows the suspected faulty coil. It is generally recommended to replace the coils at the same time the spark plugs are replaced.
Misfires can happen for various reasons. Could be as simple as bad fuel or the fuel pump sucking in some sediments from the tank. Or it could be a coil that is on the way out. Could also be a faulty spark plug, even if they are brand new. Somebody with an E63 recently destroyed their engine after the spark plugs were changed. One of the new spark plugs was faulty and a piece of the insulator broke off and fell into the combustion chamber, destroying the cylinder. Luckily there's a 1 year warranty on parts and workmanship if the service is done at a dealership, so in their case Mercedes is covering a new engine.
The way to diagnose if it's a faulty coil, is to swap the coils between two cylinders and see if the misfire follows the suspected faulty coil. It is generally recommended to replace the coils at the same time the spark plugs are replaced.
Last edited by superswiss; Jan 3, 2026 at 05:40 PM.
Thread Starter
Member
Joined: Aug 2025
Posts: 104
Likes: 20
From: Texas
2015 ML350, 2020 BMW X7, 2005 LS430
No, that's not a misfire. The clicking is the high pressure fuel injectors. A distinctive sound of direct injection engines. An active misfire causes the CEL to flash. A flashing CEL needs immediate attention and best to shut off the engine as a misfire can cause damage to the catalytic converters if it goes on too long. A misfire also causes the engine to run rough, so it's hard to miss. However, a misfire can also be very brief and go unnoticed, other than the CEL staying on afterwards and if the misfire doesn't occur anymore for a period of time, the CEL will turn off by itself.
Misfires can happen for various reasons. Could be as simple as bad fuel or the fuel pump sucking in some sediments from the tank. Or it could be a coil that is on the way out. Could also be a faulty spark plug, even if they are brand new. Somebody with an E63 recently destroyed their engine after the spark plugs were changed. One of the new spark plugs was faulty and a piece of the insulator broke off and fell into the combustion chamber, destroying the cylinder. Luckily there's a 1 year warranty on parts and workmanship if the service is done at a dealership, so in their case Mercedes is covering a new engine.
The way to diagnose if it's a faulty coil, is to swap the coils between two cylinders and see if the misfire follows the suspected faulty coil. It is generally recommended to replace the coils at the same time the spark plugs are replaced.
Misfires can happen for various reasons. Could be as simple as bad fuel or the fuel pump sucking in some sediments from the tank. Or it could be a coil that is on the way out. Could also be a faulty spark plug, even if they are brand new. Somebody with an E63 recently destroyed their engine after the spark plugs were changed. One of the new spark plugs was faulty and a piece of the insulator broke off and fell into the combustion chamber, destroying the cylinder. Luckily there's a 1 year warranty on parts and workmanship if the service is done at a dealership, so in their case Mercedes is covering a new engine.
The way to diagnose if it's a faulty coil, is to swap the coils between two cylinders and see if the misfire follows the suspected faulty coil. It is generally recommended to replace the coils at the same time the spark plugs are replaced.
Out Of Control!!
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From: San Francisco Bay Area
2019 C63CS
I've owned this car since new and as of recently I've never felt it drive rough. Would it be fine to continue driving it for a couple hundred miles or should I get it taken to the dealer to check if the plugs are faulty since they did the work? I disconnected the main battery to see if the CEL would go away but the aux probably still gave it enough power, so it didn't do anything.
Last edited by superswiss; Jan 3, 2026 at 06:30 PM.
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Joined: May 2021
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From: US
2008 E350, 2012 ML350, 2014 E350, 2015 ML350
Got a CEL on my ML350. Took it to autozone and they gave some codes related to the battery and also a p0306 code for cyclinder 6 misfire. I just replaced the battery and it's been giving some battery under-voltage related stuff. I don't know much about engines, but the guys at autozone said it probably was due to spark plugs and coils, but I put new plugs around 5k miles ago. I don't really hear a misfire, the engine's just loud cause it's direct injected. Could you tell me what you hear in the video below. Also the audio is a lot louder than it is in person, not sure why there's a lot more rattling in the video.
On the P0306, it can be many things, but since someone disturbed that area (while changing the spark plugs) it can be wiring/connection of the coil, a damaged coil, loose spark plug (it is the most difficult to remove/install of the 6 ones), among many other reasons.
If by any chance, you decide to buy coils for THIS engine, get OE parts. non-OE parts are know to pre-energize the coils w/o even cranking the engine, and blow up the intake manifold.
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MB’s of all kinds.
How many miles? Being a ML and the newest is now 11 years old I would do the plugs and coil packs since you will be in there already. I just did the 100k mile service myself on my wife’s 2015 ML350. FCP Euro for all car parts. P0603 is a misfire in #6. Best thing is just get a kit from FCP and change it all out. OE or OEM only.
Last edited by C280 Sport; Jan 5, 2026 at 05:44 PM.
Thread Starter
Member
Joined: Aug 2025
Posts: 104
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From: Texas
2015 ML350, 2020 BMW X7, 2005 LS430
How many miles? Being a ML and the newest is now 11 years old I would do the plugs and coil packs since you will be in there already. I just did the 100k mile service myself on my wife’s 2015 ML350. FCP Euro for all car parts. P0603 is a misfire in #6. Best thing is just get a kit from FCP and change it all out. OE or OEM only.
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Out Of Control!!
Joined: Apr 2019
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
mixed M276 results
Got a CEL on my ML350. Took it to autozone and they gave some codes related to the battery and also a p0306 code for cyclinder 6 misfire. I just replaced the battery and it's been giving some battery under-voltage related stuff. I don't know much about engines, but the guys at autozone said it probably was due to spark plugs and coils, but I put new plugs around 5k miles ago. I don't really hear a misfire, the engine's just loud cause it's direct injected. Could you tell me what you hear in the video below. Also the audio is a lot louder than it is in person, not sure why there's a lot more rattling in the video.
No6 misfire can be the cheap boot between coil and plug has failed.
Try swapping your ignition parts:
- the coil/boot with No5
- the plug with No4
Read LTFT at idle.
Report results to help guide next step.
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Thread Starter
Member
Joined: Aug 2025
Posts: 104
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From: Texas
2015 ML350, 2020 BMW X7, 2005 LS430
Your M276 hot engine idle sounds excellent with direct injection timings wips and distinctive lack of injector crickets. No everyone is lucky enough to get that.
No6 misfire can be the cheap boot between coil and plug has failed.
Try swapping your ignition parts:
Read LTFT at idle.
Report results to help guide next step.
No6 misfire can be the cheap boot between coil and plug has failed.
Try swapping your ignition parts:
- the coil/boot with No5
- the plug with No4
Read LTFT at idle.
Report results to help guide next step.
Out Of Control!!
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Your ECU connectors look perfectly clean.
I don't think we have evidence of rodents involved with your No6 misfires.
Lets see if coil does fix No6
else you can swap/inspect the spark plug itself.
I don't think we have evidence of rodents involved with your No6 misfires.
Lets see if coil does fix No6
else you can swap/inspect the spark plug itself.
Last edited by CaliBenzDriver; Jan 7, 2026 at 12:31 AM.
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W212 MY'14 M276-3.5NA @75kMi
If that cylinder No6 does stay fixed with 1x new coil,
then I would replace the remaining 5x other coils/boots so ALL the sparks are exactly identical.
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Joined: Jul 2024
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From: UK, Oxfordshire
C350 NA
Quick question on the M276 NA. Mine is a 2012 C350CGI.
I've had a misfire on cyl 1 ( P0301) I cleared the fault code and it's running well again, the code has not come back yet.
Looking up replacement ignition coils, the fiche seems to suggest the left and right banks have different coils. Or is it just the tubes going down to the top of the plug that are right and left handed ?
I'm looking at ordering a BERU ignition coil, ZSE093, which looks like OE.
TIA
I've had a misfire on cyl 1 ( P0301) I cleared the fault code and it's running well again, the code has not come back yet.
Looking up replacement ignition coils, the fiche seems to suggest the left and right banks have different coils. Or is it just the tubes going down to the top of the plug that are right and left handed ?
I'm looking at ordering a BERU ignition coil, ZSE093, which looks like OE.
TIA
MBWorld Fanatic!
Joined: May 2021
Posts: 2,524
Likes: 2,041
From: US
2008 E350, 2012 ML350, 2014 E350, 2015 ML350
Quick question on the M276 NA. Mine is a 2012 C350CGI.
I've had a misfire on cyl 1 ( P0301) I cleared the fault code and it's running well again, the code has not come back yet.
Looking up replacement ignition coils, the fiche seems to suggest the left and right banks have different coils. Or is it just the tubes going down to the top of the plug that are right and left handed ?
I'm looking at ordering a BERU ignition coil, ZSE093, which looks like OE.
TIA
I've had a misfire on cyl 1 ( P0301) I cleared the fault code and it's running well again, the code has not come back yet.
Looking up replacement ignition coils, the fiche seems to suggest the left and right banks have different coils. Or is it just the tubes going down to the top of the plug that are right and left handed ?
I'm looking at ordering a BERU ignition coil, ZSE093, which looks like OE.
TIA
https://mbworld.org/forums/e-class-w...ml#post9003342
That issue is well-documented in several forums, and a few videos
Last edited by JCM_MB; Mar 4, 2026 at 04:44 PM.
Out Of Control!!
Joined: Apr 2019
Posts: 11,923
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
No1 has misfired
before buying coils... do swap your parts around: coil/boot/plug.
Don't waste a chance to troubleshoot what your problem really is.
See where misfire return if it moves away from No1.
How many miles on your :
Don't waste a chance to troubleshoot what your problem really is.
See where misfire return if it moves away from No1.
How many miles on your :
- coils ?
- boots ?
- plugs ?
- engine ?
- fuel filter?
Last edited by CaliBenzDriver; Mar 4, 2026 at 09:09 PM.
