2015 Mercedes C400 (M276 Engine) – P0016 Cold Start Rattle & Slow Crank
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2015 Mercedes benz c400
2015 Mercedes C400 (M276 Engine) – P0016 Cold Start Rattle & Slow Crank
Hey everyone, looking for some insight on a persistent issue with my 2015 Mercedes C400.
The Issue:
I've had a P0016 – Crankshaft Position / Camshaft Position Correlation (Bank 1, Sensor A) code for about 2 years now. On cold starts, the car takes 4–5 seconds to crank before it fires, accompanied by a metallic rattling noise that disappears completely once the engine is running. No rattling at all after it starts — purely a cold start symptom.
Key observation: When I clear the code with my OBD reader, the car starts immediately and without any rattling. However, the check engine light and P0016 code return within about a minute of driving.
Videos attached — I found a video on the internet that has the same the rattle on startup (https://www.reddit.com/r/mechanics/c...nd_on_startup/) or (
)
What shops have said:
Two shops (including a Mercedes specialist) diagnosed it but couldn't pinpoint the exact root cause with confidence. Both quoted me around $11,000 CAD for repairs. I've attached their diagnostic report/quote. Needless to say I'm looking for a second opinion before pulling the trigger on anything.
My current thinking:
Based on what I've read, I'm leaning toward a failing camshaft adjuster (VVT phaser/solenoid) rather than a full cylinder head replacement. From what I understand about the M276 engine specifically, the camshaft adjuster can fail to hold oil pressure — so on startup it bleeds down, can't lock into position fast enough, and causes that brief rattle until oil pressure builds. That would also explain why clearing the code momentarily "resets" the system and the car starts clean before the ECU re-detects the timing discrepancy.
Other possibilities I've considered:
The Issue:
I've had a P0016 – Crankshaft Position / Camshaft Position Correlation (Bank 1, Sensor A) code for about 2 years now. On cold starts, the car takes 4–5 seconds to crank before it fires, accompanied by a metallic rattling noise that disappears completely once the engine is running. No rattling at all after it starts — purely a cold start symptom.
Key observation: When I clear the code with my OBD reader, the car starts immediately and without any rattling. However, the check engine light and P0016 code return within about a minute of driving.
Videos attached — I found a video on the internet that has the same the rattle on startup (https://www.reddit.com/r/mechanics/c...nd_on_startup/) or (
What shops have said:
Two shops (including a Mercedes specialist) diagnosed it but couldn't pinpoint the exact root cause with confidence. Both quoted me around $11,000 CAD for repairs. I've attached their diagnostic report/quote. Needless to say I'm looking for a second opinion before pulling the trigger on anything.
My current thinking:
Based on what I've read, I'm leaning toward a failing camshaft adjuster (VVT phaser/solenoid) rather than a full cylinder head replacement. From what I understand about the M276 engine specifically, the camshaft adjuster can fail to hold oil pressure — so on startup it bleeds down, can't lock into position fast enough, and causes that brief rattle until oil pressure builds. That would also explain why clearing the code momentarily "resets" the system and the car starts clean before the ECU re-detects the timing discrepancy.
Other possibilities I've considered:
- Stretched or worn timing chain (chain slap on cold start is a known M276 issue)
- Worn timing chain tensioners (Mercedes has a service bulletin on this for the M276/M278 engines)
- Faulty camshaft or crankshaft position sensor
- Low oil pressure or dirty/wrong oil affecting VVT response
- Has anyone dealt with P0016 specifically on the M276 engine (C400, E400, GLE)? What ended up being the fix?
- Does the "clears fine, code returns in 1 minute" pattern point more toward a sensor issue vs. a mechanical timing issue?
- Is $11,000 CAD a reasonable quote for this, or does that seem high depending on what actually needs to be replaced?
- Would you rule out a cylinder head issue given that the rattle only appears on cold start and not at all once running? I already replaced the belt and stuff like that.
MBWorld God!
Joined: Dec 2019
Posts: 31,852
Likes: 6,198
Hey everyone, looking for some insight on a persistent issue with my 2015 Mercedes C400.
The Issue:
I've had a P0016 – Crankshaft Position / Camshaft Position Correlation (Bank 1, Sensor A) code for about 2 years now. On cold starts, the car takes 4–5 seconds to crank before it fires, accompanied by a metallic rattling noise that disappears completely once the engine is running. No rattling at all after it starts — purely a cold start symptom.
Key observation: When I clear the code with my OBD reader, the car starts immediately and without any rattling. However, the check engine light and P0016 code return within about a minute of driving.
Videos attached — I found a video on the internet that has the same the rattle on startup (https://www.reddit.com/r/mechanics/c...nd_on_startup/) or (https://www.youtube.com/watch?v=5Wp5ev0hTeY&t=9s)
What shops have said:
Two shops (including a Mercedes specialist) diagnosed it but couldn't pinpoint the exact root cause with confidence. Both quoted me around $11,000 CAD for repairs. I've attached their diagnostic report/quote. Needless to say I'm looking for a second opinion before pulling the trigger on anything.
My current thinking:
Based on what I've read, I'm leaning toward a failing camshaft adjuster (VVT phaser/solenoid) rather than a full cylinder head replacement. From what I understand about the M276 engine specifically, the camshaft adjuster can fail to hold oil pressure — so on startup it bleeds down, can't lock into position fast enough, and causes that brief rattle until oil pressure builds. That would also explain why clearing the code momentarily "resets" the system and the car starts clean before the ECU re-detects the timing discrepancy.
Other possibilities I've considered:
The Issue:
I've had a P0016 – Crankshaft Position / Camshaft Position Correlation (Bank 1, Sensor A) code for about 2 years now. On cold starts, the car takes 4–5 seconds to crank before it fires, accompanied by a metallic rattling noise that disappears completely once the engine is running. No rattling at all after it starts — purely a cold start symptom.
Key observation: When I clear the code with my OBD reader, the car starts immediately and without any rattling. However, the check engine light and P0016 code return within about a minute of driving.
Videos attached — I found a video on the internet that has the same the rattle on startup (https://www.reddit.com/r/mechanics/c...nd_on_startup/) or (https://www.youtube.com/watch?v=5Wp5ev0hTeY&t=9s)
What shops have said:
Two shops (including a Mercedes specialist) diagnosed it but couldn't pinpoint the exact root cause with confidence. Both quoted me around $11,000 CAD for repairs. I've attached their diagnostic report/quote. Needless to say I'm looking for a second opinion before pulling the trigger on anything.
My current thinking:
Based on what I've read, I'm leaning toward a failing camshaft adjuster (VVT phaser/solenoid) rather than a full cylinder head replacement. From what I understand about the M276 engine specifically, the camshaft adjuster can fail to hold oil pressure — so on startup it bleeds down, can't lock into position fast enough, and causes that brief rattle until oil pressure builds. That would also explain why clearing the code momentarily "resets" the system and the car starts clean before the ECU re-detects the timing discrepancy.
Other possibilities I've considered:
- Stretched or worn timing chain (chain slap on cold start is a known M276 issue)
- Worn timing chain tensioners (Mercedes has a service bulletin on this for the M276/M278 engines)
- Faulty camshaft or crankshaft position sensor
- Low oil pressure or dirty/wrong oil affecting VVT response
- Has anyone dealt with P0016 specifically on the M276 engine (C400, E400, GLE)? What ended up being the fix?
- Does the "clears fine, code returns in 1 minute" pattern point more toward a sensor issue vs. a mechanical timing issue?
- Is $11,000 CAD a reasonable quote for this, or does that seem high depending on what actually needs to be replaced?
- Would you rule out a cylinder head issue given that the rattle only appears on cold start and not at all once running? I already replaced the belt and stuff like that.
Out Of Control!!
Joined: Apr 2019
Posts: 11,812
Likes: 6,707
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
luck of draw
Hey everyone, looking for some insight on a persistent issue with my 2015 Mercedes C400.
The Issue:
I've had a P0016 – Crankshaft Position / Camshaft Position Correlation (Bank 1, Sensor A) code for about 2 years now. On cold starts, the car takes 4–5 seconds to crank before it fires, accompanied by a metallic rattling noise that disappears completely once the engine is running. No rattling at all after it starts — purely a cold start symptom.
Key observation: When I clear the code with my OBD reader, the car starts immediately and without any rattling. However, the check engine light and P0016 code return within about a minute of driving.
Videos attached — I found a video on the internet that has the same the rattle on startup (https://www.reddit.com/r/mechanics/c...nd_on_startup/) or (https://www.youtube.com/watch?v=5Wp5ev0hTeY&t=9s)
What shops have said:
Two shops (including a Mercedes specialist) diagnosed it but couldn't pinpoint the exact root cause with confidence. Both quoted me around $11,000 CAD for repairs. I've attached their diagnostic report/quote. Needless to say I'm looking for a second opinion before pulling the trigger on anything.
My current thinking:
Based on what I've read, I'm leaning toward a failing camshaft adjuster (VVT phaser/solenoid) rather than a full cylinder head replacement. From what I understand about the M276 engine specifically, the camshaft adjuster can fail to hold oil pressure — so on startup it bleeds down, can't lock into position fast enough, and causes that brief rattle until oil pressure builds. That would also explain why clearing the code momentarily "resets" the system and the car starts clean before the ECU re-detects the timing discrepancy.
Other possibilities I've considered:
The Issue:
I've had a P0016 – Crankshaft Position / Camshaft Position Correlation (Bank 1, Sensor A) code for about 2 years now. On cold starts, the car takes 4–5 seconds to crank before it fires, accompanied by a metallic rattling noise that disappears completely once the engine is running. No rattling at all after it starts — purely a cold start symptom.
Key observation: When I clear the code with my OBD reader, the car starts immediately and without any rattling. However, the check engine light and P0016 code return within about a minute of driving.
Videos attached — I found a video on the internet that has the same the rattle on startup (https://www.reddit.com/r/mechanics/c...nd_on_startup/) or (https://www.youtube.com/watch?v=5Wp5ev0hTeY&t=9s)
What shops have said:
Two shops (including a Mercedes specialist) diagnosed it but couldn't pinpoint the exact root cause with confidence. Both quoted me around $11,000 CAD for repairs. I've attached their diagnostic report/quote. Needless to say I'm looking for a second opinion before pulling the trigger on anything.
My current thinking:
Based on what I've read, I'm leaning toward a failing camshaft adjuster (VVT phaser/solenoid) rather than a full cylinder head replacement. From what I understand about the M276 engine specifically, the camshaft adjuster can fail to hold oil pressure — so on startup it bleeds down, can't lock into position fast enough, and causes that brief rattle until oil pressure builds. That would also explain why clearing the code momentarily "resets" the system and the car starts clean before the ECU re-detects the timing discrepancy.
Other possibilities I've considered:
- Stretched or worn timing chain (chain slap on cold start is a known M276 issue)
- Worn timing chain tensioners (Mercedes has a service bulletin on this for the M276/M278 engines)
- Faulty camshaft or crankshaft position sensor
- Low oil pressure or dirty/wrong oil affecting VVT response
- Has anyone dealt with P0016 specifically on the M276 engine (C400, E400, GLE)? What ended up being the fix?
- Does the "clears fine, code returns in 1 minute" pattern point more toward a sensor issue vs. a mechanical timing issue?
- Is $11,000 CAD a reasonable quote for this, or does that seem high depending on what actually needs to be replaced?
- Would you rule out a cylinder head issue given that the rattle only appears on cold start and not at all once running? I already replaced the belt and stuff like that.
The PDF quote you show is related to "$10k oil in harness" which is not related to startup rattle. You can actually have both failures at once for twice the repairs.
What you describe is nothing more than the standard startup VVT rattle plus perhaps a shifted camshaft reluctor wheel.
Basic repairs may include :
- VVT (intake) gears
- Chain tensioners
- (whole camshaft !?!)
- Fresh leaking CPS (+ pigtails)
Cross your fingers you didn't wait long enough to get reluctors shifter.
Much more expensive repair: $$$$
- New camshaft part plus
- labor: valve cover out with
- labor: injectors rail out
- (in addition of VVT Gear)
> Things to consider:
How many miles has this been rattling ??
What oil grade do you use: 0W-30/40 ??
What oil schedule: 10kMi ??
Last edited by CaliBenzDriver; Apr 30, 2026 at 05:40 PM.
MBWorld God!
Joined: Dec 2019
Posts: 31,852
Likes: 6,198
Good summary and investigations.
The PDF quote you show is related to "$10k oil in harness" which is not related to startup rattle. You can actually have both failures at once for twice the repairs.
What you describe is nothing more than the standard startup VVT rattle plus perhaps a shifted camshaft reluctor wheel.
Basic repairs may include :
Cross your fingers you didn't wait long enough to get reluctors shifter.
Much more expensive repair: $$$$
> Things to consider:
How many miles has this been rattling ??
What oil grade do you use: 0W-30/40 ??
What oil schedule: 10kMi ??
The PDF quote you show is related to "$10k oil in harness" which is not related to startup rattle. You can actually have both failures at once for twice the repairs.
What you describe is nothing more than the standard startup VVT rattle plus perhaps a shifted camshaft reluctor wheel.
Basic repairs may include :
- VVT (intake) gears
- Chain tensioners
- (whole camshaft !?!)
- Fresh leaking CPS (+ pigtails)
Cross your fingers you didn't wait long enough to get reluctors shifter.
Much more expensive repair: $$$$
- New camshaft part plus
- labor: valve cover out with
- labor: injectors rail out
- (in addition of VVT Gear)
> Things to consider:
How many miles has this been rattling ??
What oil grade do you use: 0W-30/40 ??
What oil schedule: 10kMi ??
Out Of Control!!
Joined: Apr 2019
Posts: 11,812
Likes: 6,707
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
mixed high repairs
Now it's entirely possible OP needs Harness + new VVT's... is it worth fixing ?
Worth DIY'ing yes but not $16,000. repair.
Factor in other maintenance:
Next brake job
New tire set
Tstat jam
Coolant radiator leak
Car value upside down...
