My first real test... Backstory no issues for months. Seemingly single misfire right as I pulled up to park, engine light came on next time I took it out.
Xentry Both cam position sensor codes P03410 cylinder 1 , P03420 - sensor short
I am aware of the oil / wire / ecu issues - this was never neglected to that point - possible but unlikely, we'll get to this in the description.
Also worth mentioning the xentry shows 11.4 while the battery is on a charger, BUT i tested the battery in front with a meter and it's 12.5 - it seems this code is possible with low battery voltage, i'm not sure why the xentry is showing 11.3 while the meter on the battery shows 12.5 beyond i think there is a battery in back too - could it average the voltage down? not sure if that would be possible or likely.
Replaced inner most cam pos sensor on drivers side - connector was oily - I figured it was that, and that was it.
Drove a few hundred miles over about 3 weeks - misses once light comes back on shortly thereafter - Important to note, I broke the extra locking clip ( new connector on order for clip ) If this thing is vibrating in the connector, it would seemingly throw this code on a bad connection?
Xentry P03410 again only
Replaced the other pos sensor, also covered in oil, but it had been replaced before as it had the green gasket, not the black like the other one. also looked at the aforementioned connector, full of oil again.
Cleaned out the connectors with contact cleaner spray. Also replaced a magnet inner most, only because i noticed that oil had started leaking out of the bottom o-ring - did not expect that to effect anything, just needed fixed on it's own.
So that side has 2 new pos sensors and 1 new magnet.
Cleared the code drove it maybe 4 miles engine light immediately back on this time.
Xentry and both codes are now back p04310 p03420 - first thing i did was check the connector for that first sensor, with the missing extra lock - and there was a tiny bit of oil but nothing like the prior 2 times. I thought that perhaps residual oil in the connector could be causing issues.
I imagine my next logical action is to use the multi-meter to check the sensor voltage, as well as the circuit on the harness side - all of which should be a protocol on WIS, but i've not yet figured out how to use WIS in relation to Xentry or error codes. Anyone that knows i'm happy to pay for my education. Otherwise starting at the help tab and reading away.
I have not yet tested anything with a meter. This last occurence the car never missed a beat, runs great.
I've also read that 0431 can be a camshaft sensor, but that typically either prevents the car from starting at all, or will not start warm - I have no issues like that whatsoever. Not to say that's not the issue, but it seems this is electrical in nature, and either simply just that sensor vibrating itself around and throwing errors OR seemingly something more serious.
Beyond that, anyone know where the ECU is on a 2012 cls550? My guess is under the passenger seat - i'd like to pull that connector to inspect for oil just in case, as i can stop the oil flowing into the ECU if it's migrated.
starter starts the car no problem
Any thoughts in any direction would be most useful.
Winter is on it's way and soon this won't touch the roads much regardless, but I'd rather send her into hibernation strong...
if anything from the Xentry would prove useful lmk and I'll ask you how to get that info to this forum and then what it means
This last step with the multi meter should rule out the wiring harness oil ecu thing.
I'm not sure how the wires are spiced into the harness either, that would seem a logical point of failure - taking that from my fuel pump dying on my 84 datsun pickup - splice just corroded apart. No rust on this car and really clean for a 2012 imo. Dealer serviced for it's lifetime.
Guess preventative maintenance from a dealer would be too much to ask eh?
I love this thing. I want it to last as long as it can. I really don't want to give up and tag the dealer in unless it's a warranty repair, got the gold one.
timing chain stretch was also mentioned, again runs great so that wouldn't seem the obvious issue either.
Really hard to know given that connector isn't quite as snug as it should be cause of the broken anti-vibration lock.
thanks

 

UPDATE: found the Xentry "Tests" button - and I was focused on the driver's side "left" and the sensor was on the right / passenger according to the Xentry test.
I have one new sensor left. It would seem the xentry provides instruction and the wis provides the diagrams charts voltages specs etc. p03410 test was right in the middle of operating range. To be continued...

 

UPDATE: Someone was kind enough to point out the left / right designation - Merc is an international manufacturer, passenger / driver are interchangeable. Orientation is as seated in the vehicle left / right
Now knowing the orientation of the label. I also found the "tests" button in Xentry on the 341 342 codes - had no idea the Xentry literally walked you through every single step of diagnosis, with tests and all - absolute necessity - if you can't afford it, you probably shouldn't DIY either way the parts are expensive but not nearly as bad as labor.
So with that, Xentry said B5/6 ( or 6/5 ) it's the right side center most sensor that had both codes - last sensor to be replaced. 3 of the 4 had been replaced prior including the one that threw the code ( green o-ring ) one was still black, and that thing was totally full of oil. the other 3 had oil in them as well - known issue, bosch makes the sensors - bosch made my laundry dryer - bosch has no business making electrical connectors is the final word there.
Moral of the story, check the sensors every few thousand miles, or minimally at oil changes - if they leak, replace them before your harness and ECU suffer teh neglect.
Also changed out 2 batteries as i noticed oil leaks on the o-ring.
I've not yet driven to see if the code will come back. But that will happen tonight.
I'm getting nervous now, as if the sensor wasn't busted - that means it's the harness, and as i mentioned, Xentry seemingly explains testing the harness on a multi meter too.
Praying replacing the sensor that was actualy throwing the codes resolves teh issue. Otherwise got lucky with checking the wrong sensors given this seems to be one of the ways these things die.

 

resolved - it was the sensor. worth noting that every single sensor was full of oil , and 3 of the 4 had already been replaced. Those sensors are BOSCH garbage via the Mercedes dealer parts desk ( Xentry says BOSCH ) - that's the issue. Not thrilled with Mercedes to maintain this vendor given this destroys the ECU.
suppose that oil check plug / timing chain tensioner should pro-actively be replaced as well?