Hey all, I can't seem to figure out what my issue is... here's the history from thepast year:

2013 C250 1.8L Turbo (W204 - 271)

April 2024 - timing chain replaced by MB dealer (according to service records)

June 2024 - I purchased vehicle from dealer. Engine light came on within one week (P0014 & P0017). Returned to the dealer. They said they replaced a sensor and it's all good now.

August 2024 - CEL on again - same codes - Cam adjuster & magnets, VVT solenoid and Cam & Crank position sensors replaced.

October 2024 - engine blew - timing jumped, causing a chain reaction that lead to the engine imploding (for lack of better term).
Engine was replaced, and as a precaution, new timing chain, tensioner, guide rails, adjuster solenoids, vvt solenoid, sensors all replaced before new (used) engine installed. Other non-timing related parts also replaced as a precaution.

December 2024 - codes returned. Cam adjuster & magnets, VVT solenoid and Cam & Crank position sensors replaced again!

February 2025 - Same codes returned. Engine dismantled and all timing components checked, and timing reset. Also discovered 2 minor oil leaks.

May 2025 - Codes Returned yet again. Timing chain and all related components replaced for the THIRD TIME in a year. This time, the main wiring harness was also replaced. Both oil leaks also fixed at this time. Codes returned within days.

June 2025 - did not drive car - away on vacation.

July 2025 - took it to another MB dealer. All they said after hours of diag time was "replace the timing components". Grrr.

To this day, the codes are still there and intermittently, the engine shutters and idles rough. Which is exactly the same thing that started happening before the engine blew back in October. Some days, it runs perfectly, with no issues. Occasionally, the CEL will go off, then come back on, later in the day or the next day. But it always comes back on.

I'm at a loss here. I don't know what more I can possibly do. Other than maybe replace the ECU? Is it possible that the whole time it could have been a computer issue and not a mechanical issue?
And no, I can't get rid of the car - my dumb*ss still has 4 years of payments on it

HELP!?!

 

What engine. I see Canada and C250. Arent earlier years the 272 engine? Not sure what later years are, 271?

 

Sorry - 1.8L (271)

 

Whoever has been doing the diagnostics has been doing a terrible job.

 

Agreed. That's why I went to a different dealer this tie, and got the same response - "We need to replace all the parts". Even after I gave them the history, and before they brought the car in, I told them I'm done replacing parts, and I wanted to know WHY it's happening. Now I just need to know what to do next.

 

Someone in this chain of failures is either grossly incompetent or is lying. Since you still have a loan, is it covered by any type of warranty?
—What were the original DTCs and what were the symptoms?
—Failed camshaft adjusters produce a very recognizable symptom and very specific DTCs.
—What were the DTCs associated with the later CELs and what were the symptoms?
If this vehicle was serviced at MB dealers, all this information should be available in MBCA service records.
Do you have medium level mechanical expertise? If you do, it may take that to take the valve cover off and look for yourself to see what is wrong and whether things were done as described. Otherwise, a competent 3rd party may be needed.
I hate to suggest dishonesty, but this is a failure that has clear symptoms, a clearly defined repair, and should last 75,000 miles (120,000 km). Keep photos of what is found as leverage/evidence.

 

I cant imagine an engine replaced not even a year ago not being under warranty. It really should be running perfectly. Maybe a lawyer needs to get involved, but thats not what youre asking so i'll try to stick to the issue with the engine.

Are you scanning the car, you have a scanner?

Unfortunately I am only finding those code for the M272 engine. So im not sure what they are exactly for the M271. I'll have to search around some more.

 

1) Yes there is still a warranty - but that doesn't tell me WHY this keeps happening after each repair. I'm not concerned about what it costs. I want to know why.

2) The original DTC's were the same as I am getting today (P0014 & P0017). These have not changed since the first time they came on. The symptoms are also the same... The engine intermittently shutters at idle (sitting at a red light for example). But some days it runs perfectly without any issues, other than the CEL remaining on.
3) Yes I do have the expertise to check the repairs, and I was present and assisting with the repairs all along. I am 100% confident in the repairs performed to this point. And many of the new parts installed were precautionary, hoping to avoid any further issues. But that seemed to backfire on me.

I most recently took everything apart again a couple weeks ago to check all the parts, and everything checked out. This is why I'm stumped as to why the issue persists.

 

Here is the info I was given:

Mercedes fault code P001477 on the M271 engine indicates that the exhaust camshaft (cylinder bank 1) is not reaching the commanded position. This means the engine control module (ECM) is not able to adjust the camshaft to the desired position, likely due to a malfunction in the camshaft adjuster or related components.

Mercedes fault code P001762 on the M271 engine indicates an implausible exhaust camshaft position relative to the crankshaft position, meaning the timing is likely off. This can lead to rough idling, shaking, reduced acceleration, and loud noises from the exhaust. The issue often stems from problems with the timing chain, camshaft adjusters, or potentially a stretched timing chain.

All of the parts relating to these 2 codes have been replaced more than once.

Is it possible that my ECU is bad?

 

Okay, so you rule out both incompetence and dishonesty by observation. That stumps me, too. This shouldn’t be happening. Just a guess, but how about actuation of the chain tensioner? Was the release sequence done properly (I think it was reverse the chain rotation by the crankshaft pulley until a click is heard)?

That’s a remote possibility, but how could a bad ECU cause an interference failure? The total range of the adjusters is designed so that can’t occur. I think it has to be something mechanical. Maybe an ECU swap in from a donor to rule it out or verify?

 

This would be much cheaper than diving back into the timing components.

 

I'm not convinced it's the ECU either, but at this point, I'm grasping at straws as to what's causing the issue. I thought maybe if the ECU was messed up, it could be sending incorrect info to the rest of the system. But as I type that out, it seems less likely, as something of that nature would cause more issues than just the same one over and over again.

I was also told these engines are very particular about the oil they have in them. And It was an apprentice that did the last oil change on it, when the leaks were fixed. If he used a bulk 5W20 synthetic in it, could that affect pressure, resulting in this sort of issue? Or am I grasping at more straws?

And no, I do not have an invoice showing the type of oil, because I don't pay for oil changes or general maintenance, which means no receipts. I trust them to use the proper fluids, but I didn't think of it until later, that it was a first year that did it most recently.

 

The exhaust camshaft position is consistently flagged out of control both early/late.

A long nightmare with ever parts swapped including used engine + harness for very little difference....


The ECU sounds like a very fair guess to troubleshoot.
-- For all the time & ressources that were already involved, I would read live camshafts timing data corrections.
Spot a difference between hot/cold.
-- Look at signature Oily ECU connector from ECU side
-- Besides ECU any other faulty modules ??

 

hada similar issue with v8 engine , turned out to be crank sensor reading faulty

 

whole complete engine + harness were swapped after first engine blew up

 

I decided to take it to another shop for a fresh set of eyes and roll the dice to see what they come up with. Well, it turned out to be the right move, because they found codes that the other 3 (dealer included) didn't mention. According to this shop, these were stored and active codes. Pic attached with info. Not sure what to make of it, or what the next move should be. They wanted 10-15 hours labour to tear it down to dig deeper.

 

Good move... this evidence looks like your struggles should be over soon!



Exhaust cam position faults
>> The above is a unequivocal invitation to check camshaft timing mark through CPS opening, a 15mn quick job. without no timing cover or major dismantling.
Typically the camshaft reluctor ring will be found shifted.

-- There is nothing in the above fault collection that suggest a crazy ECU. Quite the opposite: it shows ECU working well!


>> In addition the heater core valve has issue (left UNPLUGGED?) - The heater is actually part of engine cooling so your best interest is to get that working

>> Turbo fault...
This read like engine missing power boost from bad vacuum supply to diaphragm?

 

Exhaust cam position faults
>> The above is a unequivocal invitation to check camshaft timing mark through CPS opening, a 15mn quick job. without no timing cover or major dismantling.
Typically the camshaft reluctor ring will be found shifted.

The cams on a M271 have the reluctor rings cast into the blank and then ground in position.

 

what do you think this could be?