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I've owned a W204 C300 with an M276 3.5L in my dream specification for about a year now. The car has a good service history and has only done 100,000 km.
One day on a cold start I got a loud rattle noise, so I quickly shut it off—I was very surprised as this was the first time the car ever made any irregular noise.
5 mins later I checked everything, turned it back on, and it has never cold-start rattled again.
The car has made an occasional warm-start rumble, so I took it to a specialist. They found a stored P002177 code. They did their tests and came to the conclusion that it needs a new intake cam adjuster Bank 2 and quoted me $3,600 AUD for the job. Later they called and said they don't want to do it—they had a look through the holes for the cam pulse wheel and said they don't do cam work.
What's really concerning me is that I thought I caught it early, but now I think the damage has been done. I'm not too sure though. The car doesn't have a single other code apparent.
I would really appreciate any information about this issue as it has created quite a panic in my mind. If anyone knows trusted specialists in Sydney please let me know.
100,000 km is quite early on the M276 NA engine for that kind of failure. Our GLK350 with M276 NA engine had 250,000+ km problem free when it was retired because of a collision. Also, if the code is only STORED and there is no CEL, it may be from that one startup rattle incident. IIRC, the ECU looks at timing codes in groups of 3. It takes 3 consecutive incidents to set a CEL, indicating a real problem. Likewise, 3 normal starts in a row will turn the CEL off again. You clearly had an incident that bears watching, but maybe no repairs are needed now. A second opinion may be in order. The code should be cleared and monitored to see if it returns, and further startup rattling would be a definite indication of a problem. Many DIYers will change the camshaft position sensor on that bank “just in case” before diving into the engine. The sensor is an easy job and the part is not very expensive. Curious as to why they turned down the repair, because the camshaft adjuster on that engine is only a medium difficulty task for a shop.
Spoke to the mechanic again today—he said the problem is right at the very very start / annoying early stage. Cam variance is still within limits (no major deviation beyond what's acceptable yet), and the car can go for a long time before any real breakdown risk.
No need for the big $10k fix right now. Just monitoring for now—code is stored only, no CEL, and rattle was only once. Will clear the code and see if it comes back.
Thanks again for the input, especially the tip about the cam position sensor and ECU logic.
here the the photos from the cam shaft position sensors. the angles are not the best but it gives an idea of what is going on
Really? Roll the dice on an engine of unknown provenance? 😑
Yes really. The car was running when it was crashed. That is why scapyards sell engines. Engines are about $700 here and if it's bad they will give you another one. Change it in one day. I'd do that 5 times before spending 10k on cams. You can buy running 204s all day for 4k.
I've put used engines in cars over 10 times, never had to pull one back out.
Yes really. The car was running when it was crashed. That is why scapyards sell engines. Engines are about $700 here and if it's bad they will give you another one. Change it in one day. I'd do that 5 times before spending 10k on cams. You can buy running 204s all day for 4k.
I've put used engines in cars over 10 times, never had to pull one back out.
I don't get paid by the hour, I get paid by the job. There are people just like me all over the planet that can swap an engine in a 204 in one day. Not you apparently.
You can swap engine or you can swap components instead... which is a faster repair?
Based on what is shown above, you'll likely need only ONE VVT PHASER (new/rebuild kit/used) - Need basic rotation test.
Tensioners will be reused
Shifted reluctor will be reset
No serpentine kit
Minimum Phasers count
> ODDITIES :
-- What's odd is the EXHAUST reluctor has shifted !
-- The stock oiling pressure issues is with unlocked INTAKE VVT's
-- So there a chance of a free fix where VVT's are 100% ok.
Last edited by CaliBenzDriver; Feb 27, 2026 at 01:55 PM.
You can swap engine or you can swap components instead... which is a faster repair?
Based on what is shown above, you'll likely need only ONE VVT PHASER (new/rebuild kit/used) - Need basic rotation test.
Tensioners will be reused
Shifted reluctor will be reset
No serpentine kit
Minimum Phasers count
> ODDITIES :
-- What's odd is the EXHAUST reluctor has shifted !
-- The stock oiling pressure issues is with unlocked INTAKE VVT's
-- So there a chance of a free fix where VVT's are 100% ok.
Yes, it would be faster to change cam phasers. If it was my car that is what I would do. Someone quoted him 10k for the job. I suggested a less expensive alternative he may consider.
Looking at the pulse wheel photos from the peep holes, none of them look shifted to me — edges/tooth positions seem aligned. The Bank 2 exhaust one appears off in the photo, but it's almost certainly just the camera angle (narrow hole + tilt makes it look misaligned when it's not). No correlation codes like P0016/P0018 to support any real shift anyway.
Everything still points to the Bank 2 intake cam adjuster starting to bleed down — that's what the P002177 is for, and it fits the occasional warm-start dieselly rumble/rattle perfectly. I think the first shop was just being extra conservative and didn't want to risk it.
I don't get paid by the hour, I get paid by the job. There are people just like me all over the planet that can swap an engine in a 204 in one day. Not you apparently.
Most definitely not me. I would never promise one of my drivers/owners a one day engine swap. The last one day swap I did was a mid ’70s Pontiac. And that was with a helper. Maybe I’m just slow.
It’s extremely unlikely we’ll ever see a 10+ year old car with low mileage anyway. Our daily usage is high, and the cars get beat to hell on secondary roads. A couple of them have to deal with off pavement duty. No 204s in the stable any longer.
However, you and @CaliBenzDriver seem to have established a rapport, so carry on.
Yes really. The car was running when it was crashed. That is why scapyards sell engines. Engines are about $700 here and if it's bad they will give you another one. Change it in one day. I'd do that 5 times before spending 10k on cams. You can buy running 204s all day for 4k.
I've put used engines in cars over 10 times, never had to pull one back out.
But that's just me.
You've been remarkably unlucky. Maybe choose your next car more thoughtfully?
So I got an oil change last weekend with 229.5 spec 5w-40. the rattle/ noise on warm starts disappeared for almost 4 days. today after sitting for 5 hours it made the noise again.
My question is based on everything we know should I just monitor the issue or is there a fix I should I go do now. how long can I leave this for?
So I got an oil change last weekend with 229.5 spec 5w-40. the rattle/ noise on warm starts disappeared for almost 4 days. today after sitting for 5 hours it made the noise again.
My question is based on everything we know should I just monitor the issue or is there a fix I should I go do now. how long can I leave this for?
Thanks In advance, this community is amazing.
This startup rattling is caused by lack of available oil pressure during startup.
In addition over stressed phaser locks are no longer able to hold camshafts in sync.
The stock oil service has been completed. Old stock oil alone can rattle all new parts.
The fix is a combination of new tensioner plus phaser on one or two banks.
The intake phasers usually begin rattling long before the exhaust get involved.
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M276 code P002177 huge $10k bill??
Update on my C300 M276 P002177 issue
